McsM^c$am 

EXPERIMENT  STATION 

OF  THE 

HAWAIIAN  SUGAR  PLANTERS'  ASSOCIATION 


The  Improvement  of  Plants 
Through  Bud  Selection 


BY 


A.  D.  SHAMEL 

Physiologist  of  the  U.  S.  Department  of  Agriculture 


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HONOLULU,  HAWAII 


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Jfortl(  fflaroltna  Stair  fflolkg? 

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This  BOOK  may  be  kept  out  TWO  WEEKS 
ONLY,  and  is  subject  to  a  fine  of  PIVE 
CENTS  a  day  thereafter.   It  is  due  on  the  day 

indicated  belovv-: 


EXPERIMENT  STATION 

OF  THE 

HAWAIIAN  SUGAR  PLANTERS'  ASSOCIATION 


The  Improvement  of  Plants 
Through  Bud  Selection 


BY 

A.  D.  SHAMEL 

Physiologist  of  tlie  U.  S.  Department  of  Agriculture 


HONOLULU,  HAWAII 


LETTER  OF  TRANSMITTAL 


To  the  Experiment  Station  Comuiittee  of  the 
Hawaiian  Sugar  Planters'  Association, 
Honolulu,  T.  H. 

Dear  Sirs  : — 

I  transmit  herewith  for  pubhcation  a  paper  by  Mr.  A.  D.  Shamel.  Physiolo- 
gist of  the  U.  S.  Department  of  Agriculture,  entitled  "The  Improvement  of 
Plants  Through  Bud  Selection."  This  paper  was  presented  by  Mr.  Shamel  at  a 
meeting  of  the  Social  Science  Association  of  Honolulu,  March  7,  1921,  and  is 
published  through  the  courtesy  of  that  organization. 


Respectfully, 


H.  P.  Agee, 

Director. 


PREFACE 


The  present  paper  was  prepared  at  the  suggestion  of  Mr.  Alonzo  Gartley 
for  presentation  to  the  members  of  the  Social  Science  Association  of  Honolulu. 
After  reading,  the  members  of  this  Association  kindly  consented  to  the  request  of 
Mr.  H.  P.  Agee  that  it  be  published  by  the  Experiment  Station  of  the  Hawaiian 
Sugar  Planters'  Association.  In  this  paper  the  writer  has  attempted  to  briefly 
present  his  point  of  view  and  experience  in  the  work  for  the  improvement  of 
certain  economic  plants  through  bud  selection.  His  experience  has  covered  about 
twenty  years  of  active  work  with  plant  improvement,  mainly  with  corn,  tobacco, 
asparagus,  citrus  fruits,  and  some  other  farm  crops.  Individual  sugar  cane  plant 
studies  were  begun  in  February,  1920,  by  the  writer  and  associates  of  the 
Experiment  Station  of  the  Hawaiian  Sugar  Planters'  Association.  The  writer 
believes  that  the  results  of  this  effort  will  be  of  particular  scientific  interest  and 
great  commercial  importance. 

A.  D.  Shamel. 

March  12,  1921. 


"fTfS"^ 


CONTENTS 


Page 

Plaait    Improvement 1 

Definition  of  the  Terms  Bud  Yariatiou  and  Bud  Selection 2 

Objects    of   Bud    Selection    4 

The  Origin  of  Varieties  from  Bud  Mutations 4 

The  Isolation  of  Strains  in  Established  Varieties 12 

The   Elimination    of    Undesirable    Strains 15 

The  Amelioration  of  Varieties  and  Strains  Through  Bud   Selection 15 

Individual  Plant   Performance   Eecords    16 

The   Commercial  Utilization  of  Individual  Plant  Eecords 20 

The  Selection  of  Superior  Parent  Plants 21 

Progeny    Tests    21 

The  Scientific  Study  of  Bud  Mutations  and  Bud  Selection 22 

Pioneers  in  Bud  Mutation  and  Selection  Work 22 

Summary     23 

Literature   Cited    24 

Explanation  of  Plates  27 


V>i..<v;.^tJ 


The  Improvement  of  Plants  Through  Bud 
Selection 

Plant  Improvement. 

We  are  indebted  to  Charles  Darwin  for  much  of  our  knowledge  of  the  be- 
havior of  animals  and  plants  under  domestication  (14,  15).  His  investigations 
established  many  of  the  principles  of.  and  laid  the  foundation  for,  the  further 
scientific  study  of  organic  evolution.  The  records  of  his  observations  and  experi- 
ments with  plants  have  furnished  a  large  amount  of  fundamentally  important 
data  and  reliable  information  which  has  constituted  the  basis  for  much  of  the 
recent  constructive  work  for  plant  improvement.  He  states  that  the  conscious 
or  unconscious  selection  of  superior  plants  for  propagation  by  man  has  been 
carried  on  for  about  as  long  a  time  as  agriculture  has  existed.  He  found  m 
ancient  Chinese  encyclopedias  ( 15 ),  translated  by  the  Jesuits  in  the  LSth  cen- 
tury, records  of  recommendations  for  the  preservation  and  propagation  of  the 
best  plants,  the  choice  of  large  seeds  for  planting,  and  the  history  of  an  improved 
variety  of  rice  secured  through  the  selection  and  propagation  of  superior  plants 
by  the  Emperor  Khang-hi.  Rice  is  one  of  the  best  examples  of  the  value  of  plant 
improvement  work.  At  the  present  time  there  exist  more  than  5,000  local  varie- 
ties in  diiTerent  rice-growing  districts  of  the  world  which  have  been  developed 
through  plant  selection  and  propagation. 

The  sexuality  of  plants  was  demonstrated  by  Camerarius  in  1691.  The  first 
hybrid  of  which  we  have  a  record  was  made  by  Thomas  Fairchild,  an  EngHsh 
gardener,  in  1719.  Knight,  an  eminent  English  student  of  plant  life,  contributed 
a  large  amount  of  information  to  our  knowledge  of  plant  hybridization.  Van 
Mons,  a  Belgian  horticulturist,  produced  a  number  of  improved  varieties  of  plants 
through  selection. 

The  re-discovery  of  Mendel's  famous  law  in  1900  (3)  and  the  publication 
of  De  Vries'  mutation  theory  in  the  following  year  (72)  marked  a  new  era  in 
plant  improvement.  These  contributions  stimulated  a  widespread  interest  in  the 
study  of  plant  improvement  which  has  been  unequaled  in  the  history  of  agricul- 
ture. A  large  number  of  investigators  are  now  devoting  their  entire  time  and 
energy  to  a  study  of  the  various  phases  of  this  subject.  Many  universities  have 
inaugurated  courses  of  instruction  and  study  for  students  along  these  lines.  A 
number  of  research  institutions  have  been  established  in  the  United  States  and 
abroad  for  the  purpose  of  investigating  the  fundamental  principles  underlying 
the  work  of  plant  improvement.  Several  commercial  organizations  have  been 
built  up  for  the  sole  purpose  of  carrying  on  practical  plant  improvement  work  for 
particular  crops.  As  a  result  of  this  intensive  and  systematic  activity,  plant  im- 
provement has  become  a  subject  of  great  scientific  interest  and  large  commercial 
importance  during  recent  years. 

Much  of  the  pioneer  work  for  plant  improvement  has  been  carried  on  with 
sexually  reproduced  plants.  In  science,  sex,  fecundation  and  the  behavior  of 
hybrid  plants  have  received  the  major  share  of  attention.  In  practice,  seed  se- 
lection has  been  the  most  important  phase  of  plant  improvement  work.     While 


n    M    H1LU  UBRARY 


it  has  been  known  for  a  long  time  that  bud  variation  occurs  in  vegetatively  propa- 
gated plants,  the  study  of  this  phenomenon  has  been  somewhat  neglected  for 
several  reasons.  It  has  been  quite  generally  believed  that  when  an  asexually 
propagated  variety  has  become  established  no  further  selection  is  necessary.  The 
reasons  for,  and  the  necessity  of,  selection  of  plants  grown  from  seed  have  become 
matters  of  common  knowledge.  On  the  other  hand,  the  causes  of  bud  variations 
are  not  fully  understood  as  yet,  the  extent  and  frequency  of  this  phenomenon 
have  not  been  determined  except  in  the  case  of  a  few  plants,  and  the  facts  con- 
cerning the  importance  of  bud  variation  and  bud  selection  in  the  amelioration  of 
plants  are  not  widely  understood.  Furthermore,  the  scientific  study  of  seeds 
produced  under  controlled  conditions  and  of  the  behavior  of  the  plants  grown 
from  them  provides  particularly  convenient  and  fascinating  material  for  investi- 
gation and  demonstration.  The  results  of  such  study  have  often  been  extremely 
spectacular  and  have  attracted  a  deservedly  vital  interest  in  the  minds  of  the 
general  public.  These  and  other  related  conditions  have  naturally  led  to  a  con- 
centration of  interest,  both  from  the  scientific  and  commercial  standpoints,  in 
this  phase  of  plant  improvement  and  to  a  lack  of  interest  in  similar  work  with 
vegetatively  propagated  plants.  The  purpose  of  this  paper  is  to  present  evidence 
to  show  that  bud  variations  are  of  frequent  occurrence  in  many  plants  and  to 
suggest  the  importance  of  bud  selection  in  the  economic  improvement  of  those 
plants.  This  discussion  will  be  largely  confined  to  the  practical  application  of 
bud  selection  work  in  the  improvement  of  certain  agricultural  crop  plants  which 
are  of  commercial  value  and  importance  and  which  are  propagated  without  refer- 
ence to  sexual  reproduction. 

Definition  of  the  Terms  Bud  Variation  and  Bud  Selection. 

The  term  bud  variation,  as  we  understand  it,  applies  to  any  variations  that 
take  place  in  the  soma  of  the  plant  as  distinguished  from  the  variations  appar- 
ently caused  by  sexual  reproduction  and  shown  by  the  behavior  of  seedlings. 
Webber  states  {77)  in  this  connection  *  *  *  "from  our  present  knowledge 
of  the  cytology  of  heredity  we  would  assume  that  hereditary  changes  such  as 
those  manifested  by  bud  variation,  as  well  as  seedling  variations,  are  due  to  re- 
arrangements of  the  hereditary  units  or  anlagen  which  occur  during  cell  division. 
In  the  case  of  seedling  variation  we  assume  that  this  rearrangement  takes  place 
primarily  during  the  progress  of  the  reduction  division  that  precedes  the  forma- 
tion of  sexual  cells.  So  far  as  microscopic  investigations  go  we  have  no  evi- 
dence that  would  strengthen  the  idea  of  such  a  redistribution  of  characters  ever 
taking  place  in  somatic  cells.  However,  we  have  the  strongest  of  all  possible 
proofs  that  it  does  occur  in  the  fact  that  in  bud  variation  we  get  segregations  of 
character  analogous  to  the  segregations  of  seedlings." 

Bud  variations  may  be  divided  into  two  general  classes :  ( 1 )  those  which  are 
not  inherited  and  (2)  those  which  are  inherited.  The  non-heritable  variations 
include  that  type  of  variation  which  is  the  result  of  environmental  influence  and  is 
exhibited  in  the  response  of  all  kinds  of  plants  in  the  same  definite  way  to  the 
stimulation  of  environmental  factors. 


In  this  discussion  we  are  concerned  primarily  with  the  types  of  bud  variations 
which  are  inherited.  These  types  may  be  conveniently  divided  into  two  classes, 
(a)  bud  fluctuations  or  continuous  bud  variations  and  (b)  bud  mutations  or  dis- 
continuous bud  variations.  Castle  defines  fluctuations  as  "those  which  are  purely 
quantitative,  plus  or  minus,  as  compared  with  the  ]:)revailing-  racial  condition"  ( 10). 
The  value  of  bud  fluctuation  or  continuous  bud  variations  in  the  work  of  plant 
improvement  is  a  matter  of  dispute  amongst  some  investigators.  The  particular 
point  at  issue  seems  to  be  the  possibility  of  changing  the  mode  or  increasing  the 
maximum  through  the  continuous  selection  of  maximum  bud  fluctuations.  The 
experience  and  observations  of  the  writer  have  led  him  to  believe  that  by  con- 
tinuous selection  in  isolated  strains  the  mean  of  the  variation  in  the  selected  popu- 
lation may  be  raised  to  a  point  more  nearly  approximating  the  maximum  exhibi- 
tion of  the  character  in  the  strain.  This  conclusion  has  been  reached  as  the 
result  of  study  and  observations  in  the  amelioration  of  several  of  our  important 
economic  plants,  among  which  may  be  mentioned  the  increase  of  the  average 
percentage  of  oil.  protein,  and  starch  in  the  composition  of  maize  through  the 
systematic  selection  of  seed  possessing  the  maximum  amounts  of  these  elements 
in  their  composition ;  the  increase  in  the  yield  of  varieties  of  tobacco  through  the 
systematic  selection  of  seed  from  the  best  individual  plants ;  the  increase  in  yield 
of  violets  through  the  selection  and  propagation  of  cuttings  from  the  most  pro- 
ductive plants ;  the  increase  in  the  yield  of  potatoes  by  the  selection  of  tubers  from 
the  high-yielding  hills;  the  improvement  in  the  yield  of  citrus  fruits  through  the 
propagation  of  the  best-yielding  parent  trees ;  and  many  other  equally  striking 
similar  experiences.  It  is  argued  by  some  of  the  opponents  to  this  conclusion 
that  even  if  these  improvements  in  plant  behavior  have  been  effected  it  will  be 
necessary  to  continue  the  selection  by  means  of  which  they  were  secured  in  order 
to  preserve  and  maintain  them.  This  idea  may  or  may  not  be  correct,  and  even 
granting  that  it  may  be  sound  in  some  cases,  it  does  not  vitiate  the  fundamental 
importance  of  selection  in  developing  and  maintaining  improved  production.  It 
is  the  personal  opinion  of  the  writer  that  through  the  selection  of  observed  bud 
fluctuations  in  any  plant  character,  such  as  size,  number,  or  chemical  composi- 
tion, those  of  genetic  character  will  be  included  so  that  through  repeated  selec- 
tion races  will  be  developed  which  are  progressively  larger,  more  productive,  or 
otherwise  changed  in  the  direction  of  the  selection.  From  the  commercial  stand- 
point it  is  thought  that  this  phase  of  plant  breeding  is  the  most  important  one 
concerned  in  the  work  for  the  improvement  of  plants. 

The  terms  bud  mutations  or  discontinuous  bud  variations  in  this  discussion 
will  be  used  to  define  sudden  or  marked  variations  from  the  parental  forms  in 
vegetatively  propagated  plants.  Darwin  called  such  variations  bud  sports,  but 
this  term  has  been  largely  superseded  by  the  term  bud  mutation  as  proposed  by 
De  Vries.  Many  of  our  valuable  varieties  and  strains  of  cultivated  plants  have 
originated  from  bud  mutations.  It  is  probable  that  amongst  vegetatively  propa- 
gated plants  a  majority  of  the  important  commercial  varieties  have  originated  in 
this  way.     In  seed  propagated  plants,  it  is  the  writer's  conviction  that  a  consid- 


crable  number  of  important  varieties,  wliicli  are  commonly  thought  to  have  arisen 
from  crossing,  have,  as  a  matter  of  fact,  originated  as  bud  mutations. 

The  term  bud  selection  as  used  in  this  paper  may  be  defined  as  the  selection 
and  propagation  of  heritable  bud  variations  which,  for  one  reason  or  another,  are 
better  suited  for  cultivation  than  the  parent  i)lants.  Bud  variations  are  of  no 
value  in  the  work  for  the  improvement  of  plants  unless  they  are  preserved  and 
propagated.  Their  preservation  depends  wholly  upon  selection.  It  naturally 
follows,  then,  that  bud  selection  is  the  agency  through  which  bud  variations  are 
perpetuated  and  utilized  in  the  work  of  plant  improvement. 

Objects  of  Bud  Selection. 

The  fundamental  objects  of  bud  selection  in  the  work  of  plant  improvement 
may  be  classed  as  follows :  ( 1 )  to  secure  new  and  better  varieties  of  plants 
through  the  selection  and  propagation  of  striking  and  valuable  bud  mutations ; 
(2)  to  isolate  strains  of  established  varieties  which  show  characteristics  of  greater 
merit  or  value  than  those  of  the  parent  varieties;  and  (3)  to  bring  the  average 
performance  of  the  population  of  a  strain  or  variety  up  to  that  exhibited  by  the 
maximum  individual  performance  or  as  nearly  so  as  is  found  to  be  practical. 

The  Origin  of  Varieties  from  Bud  Mutations. 

An  impressive  number  of  important  cultivated  varieties  of  plants  are  defi- 
nitely known  to  have  originated  from  bud  mutations  (8,  15,  13).  This  number  is 
probably  only  a  small  fraction  of  the  actual  total  number  of  valuable  varieties 
which  have  originated  in  this  way.  This  condition  arises  from  the  fact  that 
many  of  the  supposed  variations  in  seedlings  which  have  been  selected  and  propa- 
gated as  new  varieties  were  doubtless  the  result  of  the  seeds  having  come  from 
different  branches  of  the  parent  plants.  These  branches  as  a  result  of  bud 
variations  transmitted  to  the  seeds  their  different  tendencies  which  were  discov- 
ered as  variations  in  the  plants  grown  from  these  seeds.  In  such  instances  the 
originators  of  the  varieties  propagated  from  such  selected  variations  have  often 
assumed  that  the  variations  w-ere  the  result  of  hybridization  or  other  sexual 
influences,  when  as  a  matter  of  fact  they  are  actually  the  result  of  bud  variation. 

It  will  be  possible  in  this  paper  to  refer  to  only  a  small  number  of  the  known 
cases  of  valuable  varieties  of  plants  which  have  originated  from  bud  mutations. 
A  few  typical  instances  in  different  plant  groups  will  be  cited  in  order  to  empha- 
size the  importance  of  this  factor  in  plant  improvement  work  and  to  indicate 
something  of  the  possibilities  of  further  effort  along  this  line. 

Many  varieties  of  roses  have  originated  from  bud  mutations.  Carriere  (8) 
gives  in  his  account  of  bud  varieties  published  in  1865  a  list  of  fifty  standard 
rose  varieties  known  to  have  originated  from  bud  mutations  and  states  that  no 
attempt  was  made  to  make  the  list  complete.  The  1919  Annual  of  the  American 
Rose  Society  contains  a  list  ( 25 )  of  429  varieties  of  American  roses,  of 
which  116,  or  more  than  25  per  cent,  are  definitely  known  to  have  originated  from 
bud  mutations,  for  the  most  part  within  the  past  twenty-five  years.     Carriere  (8) 


and  Darwin  (15)  both  present  evidence,  which  has  been  confirmed  repeatedly, 
that  the  moss  rose  varieties  have  originated  from  bud  mutations  and,  in  turn, 
smooth  branch  varieties  have  sprung  from  moss  varieties  through  bud  variations. 
For  example,  the  common  dou1)le  moss  rose  ori«^inated  from  the  smooth-l:)ran 
Provence  rose  by  bud  variation.  The  moss  rose  has  produced  the  Provence  rose 
in  which  the  branches  are  partially  or  wholly  destitute  of  moss. 

From  the  Killarney  rose,  solid  pink  in  color,  a  large  number  of  varieties 
have  been  secured  through  the  selection  of  bud  mutations  (38).  These  bud  varie- 
ties have  dififered  in  color  from  white  to  red,  in  flower  arrangement  from  semi- 
doubles  to  doubles,  and  in  habit  of  growth  from  bush  to  climbing  forms.  Amongst 
these  varieties  may  be  mentioned  the  White  Killarney,  Dark  Pink  Killarney, 
Champ  W'eiland,  Killarney  Queen,  Double  White  Killarney,  Double  Pink  Killar- 
nev,  Red  Killarney,  Killarney  Brilliant,  Climbing  Killarney  (pink),  and  Climbing 
White   Killarney. 

The  Ophelia,  a  pink  rose,  is  a  variety  of  comparatively  recent  introduction 
which  is  deservedly  popular  at  the  present  time.  This  variety  is  very  prolific  in 
the  production  of  bud  mutations  (71),  the  most  important  of  which  include  the 
Ophelia  Supreme,  having  light  rose-pink  flowers ;  Rosalind,  with  coral-pink 
flowers,  clianging  to  apricot-pink  ;  Silvia,  having  sulphur-yellow  flowers,  changing 
to  creamy  shaded ;  Evelyn,  with  larger  flowers  of  a  deeper  shade  and  larger 
blooms ;  Rose  Pink  Ophelia,  having  smaller  flowers  but  flowering  more  freely 
than  the  Ophelia ;  May  Martin,  with  mustard-yellow  flowers ;  Madame  Butterfly, 
with  flowers  of  greatly  intensified  color ;  White  Ophelia,  having  white  flowers ; 
and  other  varieties  with  flowers  of  varying  shades  of  color  and  different  types 
of  foliage. 

The  rose  varieties  having  a  climbing  habit  of  growth  have  practically  all 
originated  as  bud  mutations  from  bush  forms  (25).  Examples  of  this  phenome- 
non include  the  Climbing  Bridesmaid,  the  Climbing  Cecile  Briinner,  the  Climbing 
Frau  Karl  Druschki,  the  Climbing  La  France,  and  the  Climbing  Rhea  Reid.  The 
1919  Annual  of  the  American  Rose  Society  contains  a  list  of  34  climbing  varie- 
ties of  recent  American  origin  which  have  been  propagated  from  bud  muta- 
tions  (25). 

In  chrysanthemums,  a  large  proportion  of  the  present  cultivated  varieties 
Rave  originated  from  bud  mutations.  Cramer  (13)  presents  a  list  of  400  bud 
varieties  of  the  chrysanthemum.  From  this  list  of  bud  varieties  the  following 
examples  are  presented : 

Parent   Variety.  Bud   Variety.  Authority. 

Alcester    (Lord),   1882.  Mr.  Robert  Murdie,   1888.  The   Garden,   90,   I,   1-45. 

Inflected,   butter-yellow.  Inflected,    salmon-yellow. 

Andiguier    (Edward),   1886.  Mrs.   William  Walters,   1887.  The  Garden,  88,  II,  498. 

Jap.,  brown,  purple,  Jap.,  Carmine, 

silver  back.  bronze-gold   back. 

Avalanche,    1887.  Edw.   Beckett,   1892.  de  Meulenaese,  II,  49. 

Snow-white.  Jap.,   dark   gold-yellow. 


In  1822,  twenty-seven  varieties  of  chrysanthemums  were  cultivated  in  Eng- 
land, part  of  which  had  been  imported,  and  some  of  which  had  originated  from 
the  imported  varieties  through  bud  mutation.  In  1836  three  Chinese  varieties 
were  imported  which  bore  pink,  speckled,  and  flesh-colored  flowers,  respectively. 
The  next  year  a  single  plant  bore  all  three  of  these  forms. 

Chrysanthemum  bud  mutations  frequently  occur  in  the  branches  of  the 
plants  and  occasionally  in  the  suckers.  They  may  be  propagated  in  either  form. 
The  stability  of  the  bud  mutations  must  be  determined  by  experimental  propa- 
gations unless  it  is  a  type  which  is  known  to  be  transmitted.  The  practicability 
of  this  eft'ort  is  shown  by  the  fact  that  of  the  8,800  varieties  cultivated  in  Europe 
in  1899  more  than  5,000  were  originated  in  this  way. 

In  carnations,  many  of  the  valuable  cultivated  varieties  have  originated  as 
bud  mutations.  Dorsey  (18)  mentions  among  the  important  commercial  bud 
varieties  the  Victor,  Chicago,  White  Lawson,  White  Enchantress,  Rose  Pink 
Enchantress  and  Enchantress  Supreme. 

In  hibiscus.  Darwin  (13)  mentions  several  striking  bud  mutations,  including 
one  where  the  bud  variation  produced  flowers  and  leaves  resembling  in  shape 
those  of  another  species.  Both  the  parental  form  and  the  bud  mutation  were 
extensively  propagated  by  cuttings  and  came  perfectly  true.  Stout  (69)  records 
the  origin  of  a  dwarf  form  of  Hibiscus  ocnUroscits  as  a  mutation.  Carriere  (8) 
cites  two  instances  of  varieties  of  hibiscus  originating  from  bud  mutations,  viz., 
H.  syriacus,  variety  florc  plcuo  varicgata,  with  variegated  yellowish-white 
leaves,  appearing  in  a  green-leaved  plant  in  1858,  and  H.  syriacus,  variety  varie- 
gata,  with  remarkably  variegated  leaves,  an  example  of  which  is  shown  in  Plate  I. 
While  in  Honolulu  in  1920  the  writer's  attention  was  called  to  several  cases  of 
bud  mutation  in  hibiscus  plants,  including  double  flowers  borne  by  single-flower 
plants  and  the  development  of  branches  having  very  different  foliage  on  the  same 
stem. 

In  dahlias,  Darwin  (15)  cites  the  case  of  the  Butterfly  variety,  in  which  the 
same  plants  produced  double  and  single  flowers,  "here  white  petals  edged  with 
maroon,  there  of  a  uniform  deep  maroon."  He  also  records  the  instance  of  a 
plant  which  bore  two  different  kinds  of  self-colored  flowers  as  well  as  a  third 
kind  which  partook  of  both  colors  beautifully  intermixed.  Similar  illustrations 
of  bud  mutations  in  dahlias  have  been  repeatedly  observed  in  gardens  in  southern 
California  during  recent  years  by  the  writer,  an  example  of  which  is  shown  in 
Plate  2.  The  Le  Grand  Manitou,  a  leading  dahlia  variety  having  white  flowers 
with  purple  stripes,  has  produced  a  purple-flowered  variety,  the  Purple  Manitou, 
as  shown  in  Plate  3,  by  bud  mutation  which  is  being  cultivated  at  the  present  time 
to   some   extent. 

Many  other  instances  of  varieties  of  common  flowering  plants  arising  from 
bud  mutations  might  be  mentioned.  Bud  varieties  of  the  Sweet  William,  Snap- 
Dragon,  Stocks,  Cyclamen,  Gladiolus,  Fuchsia,  Violet,  Hydrangea,  Geranium, 
and  Evening  Primrose  are  widely  cultivated  by  gardeners  and  florists.     We  be- 


lieve,  however,  that  the  examples  already  given  are  sufficient  to  show  the  im- 
portance of  this  phenomenon  in  the  work  for  the  improvement  of  flowers. 

With  ornamental  plants  the  selection  and  propagation  of  bud  mutations  has 
provided  a  large  number  of  valuable  varieties  for  cultivation. 

The  Euonymus  varieties  are  amongst  the  most  valuable  and  widely  grown  of 
all  ornamental  plants.  Carriere  (8)  calls  attention  to  five  bud  varieties  of 
E.  Japonica,  viz.,  argcntca,  aiirca.  flavida,  fasciata,  and  calamistrata,  and  states 
that  many  other  varieties  which  differ  in  variegation  or  sometimes  by  the  form  of 
leaves  have  been  produced  by  the  selection  and  propagation  of  bud  mutations. 

Roeding  (46),  one  of  the  leading  plant  propagators  in  California,  propagates 
and  distributes  the  following  varieties  of  E.  Japonica  which  he  personally  told  the 
writer  in  August,  1919,  were  originated  from  bud  mutations :  Alho-marginata 
(silver-margined),  albo-variegata  (silver- variegated),  aureo-variegata  (golden- 
variegated),  cohimnaris  (tall-growing),  viridi-variegata  (Due  d'Anjou),  aiirco- 
inarginata  (golden-margined),  and  microphylla  (dwarf  form).  The  writer 
recently  has  found  all  of  these  variations  occurring  as  bud  mutations  in  Euony- 
mus plants  growing  in  the  vicinity  of  Riverside,  an  example  of  which  is  shown 
in  Plate  4,  and  has  complete  evidence  as  to  the  origin  of  the  above  mentioned 
cultivated  varieties  from  bud  variations. 

Pittosporum  varieties  are  now  widely  grown  as  ornamental  lawn  plants  an;l 
for  shrubbery.  They  rank  in  importance  in  this  respect  with  the  Euonymus 
varieties.  Carriere  (8)  mentions  that  P.  Tobira  varicgatum  originated  from 
P.  Tobira  as  a  bud  mutation.  This  variegated-leaved  variety  is  one  of  the  most 
popular  ones  in  California  and  has  been  repeatedly  found  by  the  writer  (52) 
occurring  as  bud  mutations  in  the  green-leaved  parental  form.  Other  mutations 
of  P.  Tobira,  differing  in  leaf-form  and  variegation,  have  been  observed  by  the 
writer  in  plants  growing  in  the  vicinity  of  Riverside,  California,  an  example  of 
which  is  shown  in  Plate  5.  Some  of  these  have  been  isolated  through  bud  selec- 
tion and  are  now  being  cultivated  to  an  increasing  extent,  an  illustration  of  which 
is  shown  in  Plate  6. 

In  Coleus,  Stout  (70)  found  that  bud  variations  are  common  and  give  rise 
to  numerous  different  types  which  may  be  quite  constant  from  the  first  or  can  be 
made  so  by  selection.  In  pedigree  cultures  he  isolated  15  distinct  varieties  through 
bud  selection  which  were  characteristically  different  in  color  patterns.  He  con- 
cludes from  his  investigations  that  in  Coleus  asexual  and  sexual  reproduction 
are  not  fundamentally  different  in  respect  to  the  extent  and  range  of  variation. 

In  ferns,  Boshnakian  (6)  states  that  in  the  common  Boston  fern  {Nephro- 
lepis  cxaltata  bostoniensis)  over  65  commercial  varieties  have  originated  as  bud 
mutations  since    1898. 

In  the  Oleander  {Ncriiim  oleander),  one  of  the  oldest  of  cultivated  orna- 
mental plants,  the  writer  found  in  1918  near  Thermal,  California,  a  branch  bud 
mutation  having  variegated  leaves  borne  by  green-leaved  plants,  as  shown  in 
Plate  7,  and  uniformly  variegated  plants  which  had  been  propagated  from  similar 
mutations. 


In  Irish  potatoes,  Carriere  (8)  shows  that  many  striking  bud  mutations 
occur  which  have  been  preserved  through  selection.  East  (19)  records  bud  mu- 
tations as  shown  by  the  color,  shape,  character  of  eyes,  and  habit  of  growth,  of 
the  tubers  which  remained  constant  in  propagation.  Gilbert  (26)  says  that  the 
principal  method  of  improving  the  Irish  potato  is  through  bud  selection. 

In  the  sweet  potato,  H.  C.  Thompson,  formerly  horticulturist  of  the  U.  S. 
Department  of  Agriculture,  in  a  personal  statement  in  1917  informed  the  writer 
that  this  plant  is  exclusively  propagated  vegetatively  and  that  all  commercially 
grown  sweet  potato  varieties  have  originated  as  bud  mutations. 

In  apples,  Hedrick  (28)  describes  four  strains  which  are  now  commonly 
accepted  as  varieties  of  the  Twenty-ounce  which  originated  as  bud  mutations. 
Farmer  (23)  describes  the  Oswego  variety  as  originating  as  a  bud  mutation  of 
the  Northern  Spy.  Fletcher  (24)  gives  an  account  of  the  Chesebro  Spy  variety 
which  originated  as  a  bud  mutation  of  the  Northern  Spy.  Mead  (34)  records  a 
mutation  of  the  Gravenstein  variety  having  fruits  w^ith  solid  red  color  which  has 
been  propagated  through  bud  selection.  A  seedless  mutation  of  the  Porter  apple 
was  discovered  and  called  to  the  writer's  attention  by  J.  A.  Dorrance  at  Scotland, 
Connecticut,  in  1913.  This  consisted  of  one  of  the  main  limbs  in  an  old  tree. 
It  has  borne  similar  fruits  each  year  since  then  and  has  been  propagated. 
Beach  (4)  describes  the  Banks  apple  as  a  mutation  of  the  Gravenstein  variety, 
tliC  Collamer  as  a  sport  of  the  Twenty-ounce,  and  the  Red  Russet  and  Olympia 
as  mutations  of  the  Baldwin  variety.  Castle  (9)  refers  to  two  strains  of  the 
\\'iliiams  apple,  one  having  conspicuously  striped  fruits  and  the  other  having 
nearly  solid  red  color.  Other  striking  mutations  in  apple  varieties  have  been 
observed,  an  example  of  which  is  shown  in  Plate  8.  including  red  and  russet 
variations  of  the  Rome  (1,  2),  oblong-shaped  Grimes  (1),  solid  dark-red  varia- 
tions of  the  striped  Ben  Davis,  and  various  shaped  fruits  in  Baldwin  apple  trees 
observed  by  the  writer  at  Seymour,  Connecticut,  during  recent  years  in  indi- 
vidual tree  performance  record  plats  of  trees  of  these  varieties  in  the  J.  H.  Hale 
orchards. 

In  peaches,  Darwin  (15)  records  peach  trees  producing  buds  which  when 
developed  into  branches  yielded  nectarines  and  that  six  named  and  several  un- 
named varieties  of  the  peach  have  thus  produced  several  varieties  of  the  nec- 
tarine. Carriere  ( 8 )  describes  two  varieties  of  the  peach,  the  carnation-flowered, 
having  a  flesh-rose  color,  and  the  many-colored-flowered,  possessing  white  striped 
colors,  which  originated  as  bud  mutations.  He  also  gives  the  willow-leaved  red 
Madeleine  and  the  laciniate-leaved  red  Madeleine  as  varieties  originating  as  bud 
sports.  Fletcher  (24)  mentions  a  white-fleshed  clingstone  or  semi-freestone  va- 
riety originating  as  a  bud  mutation  of  the  Early  Michigan.  Powell  (40)  records 
the  propagation  of  an  early  ripening  mutation  of  the  Mountain  Rose  peach.  The 
writer  found  several  branches  in  Elberta  trees  in  the  performance-record  plat 
of  this  variety  in  the  J.  H.  Hale  orchards  at  South  Glastonbury,  Connecticut,  in 
1912,  bearing  fruits  without  pubescence  and  otherwise  apparently  identical  with 
fruits  of  the  new  J.   H.   Hale  variety.     Furthermore,  branches  were   found  in 


J.  H.  Hale  peach  trees  bearing  typical  Elberta  fruits,  indicating  that  the  J.  H.  Hale 
variety  originated  as  a  bud  mutation.  The  writer  also  observed  branch  muta- 
tions in  yellow-fleshed-fruited  Elberta  trees  bearing  white-fleshed  fruits  but  other- 
wise like  the  Elberta  fruits. 

In  prunes,  a  large-fruited  variety  Coates  No.  1418,  an  illustration  of  which 
is  shown  in  Plate  9.  originating  as  a  bud  mutation  of  the  French  prune,  was 
described  by  the  writer  in  1919  (57).  Coates  propagates  commercially  no  less 
than  three  varieties  of  the  French  prune  which  have  originated  as  bud  muta- 
tions (11).  Darwin  (13)  records  that  a  tree  of  yellow  Magnum  Bonum  plum. 
forty  years  old.  I'jroduced  a  branch  mutation  which  l)(:re  red  Magnum   I'.onum^. 

In  grapes,  Carriere  (8)  states  that  bud  variation  is  comparatively  common. 
Amongst  other  examples  he  cites  the  origin  of  the  white  seedless  Corinth  as  a 
mutation  from  the  parent  seedy  variety.  Fletcher  (24)  records  the  King,  a  bud 
variety  of  the  Concord.  Paddock  (37)  gives  mammoth  or  giant  forms  of  the 
Concord  identical  with  Eaton  as  originating  from  bud  mutations  of  the  Concord. 
Ballou  ( 1 )  records  a  bud  variety  of  the  Concord  with  exceptionally  large  berries 
which  came  true  under  his  observation  for  two  successive  crops.  The  Pierce 
variety  originated  as  a  bud  mutation  from  Isabella,  according  to  Le  Long  (33). 
The  writer  has  photographed  bud  mutations  of  the  Thompson  seedless  grape,  as 
shown  in  Plate  10.  with  conspicuously  large  berries  and  different  foliage  than  that 
of  the  parent  form  from  the  vineyard  of  C.  L.  Edmunds  of  Thermal,  California. 
Roeding  has  introduced  and  propagates  commercially  a  mammoth  or  giant 
Thompson  seedless  variety  which  he  has  stated  to  the  writer  originated  as  a 
bud  mutation. 

In  pears,  Carriere  (8)  says  that  the  following  varieties  have  given  by  bud 
variation  variegated  varieties,  Duchesse  d'Angouleme.  Amanlis,  Guenette.  Saint- 
Germain,  Bergamotte  d'Automne.  Culotte  de  Suisse,  and  others.  The  writer 
observed  and  photographed  in  1918  in  commercial  pear  orchards  near  Tehachapi, 
California,  limb  mutations  in  Bartlett  pear  trees  bearing  striped  fruits  and  in 
other  instances  fruits  possessing  very  different  characteristics  of  shape,  size,  and 
color  from  the  normal  fruits  on  the  same  or  neighboring  trees,  as  shown  in  Plate 
11.  Evidence  was  found  to  indicate  that  several  of  the  strains  of  the  Bartlett 
variety  in  those  orchards,  including  the  \\'inter  Bartlett.  the  Sheep's  Nose  Bart- 
lett. and  Corrugated  Bartlett,  originated  as  bud  mutations. 

In  strawberries.  Farmer  (22)  states  that  the  Pan-American,  an  ever-bearing 
variety,  originated  as  a  bud  sport  of  the  Bismark. 

An  illustration  of  bud  variation  in  the  artichoke  is  shown  in  Plate  12. 

In  citrus  fruits,  the  investigations  of  the  writer  in  Brazil  in  1913  (17)  indi- 
cate that  the  Washington  Navel  orange,  a  typical  tree  of  which  is  shown  in  Plate 
13,  one  of  the  most  important  fruit  varieties  in  existence,  originated  as  a  bud 
mutation  of  the  Selecta  variety  at  Bahia,  Brazil,  and  was  first  propagated  in 
1820.  Reasoner  (45)  states  that  the  Foster,  a  variety  of  grapefruit  producing 
pink-colored  fruits,  originated  as  a  bud  mutation  of  the  W'alters  variety.  In  a 
letter  to  the  writer  dated  .Vugust  6,  1915.  Reasoner  describes  a  pink-fleshed  mu- 
tation of  the  Marsh  grapefruit.     A  similar  mutation  was  found  by  the  writer  in 


10 

a  Marsh  tree  on  the  L.  V.  W.  Brown  ranch  at  Riverside,  California,  in  1919  (61). 
Conner  (12)  propagates  commercially  a  variety  of  grapefruit,  the  Conner  Pro- 
lific, which  he  states  originated  as  a  bud  mutation  of  the  Bowen.  The  writer  has 
isolated  through  bud  selection  in  the  Marsh  grapefruit  variety,  as  grown  in  Cali- 
fornia, a  mutation  having  conspicuously  flattened  and  commercially  seedless  fruits 
(54,  66).  An  illustration  showing  a  typical  fruit  of  this  strain  is  shown  in  Plate 
20.  It  is  of  much  greater  commercial  value  than  the  parent  variety  and  is  now 
being  extensively  propagated  by  nurserymen  in  California. 

In  cotton,  the  Pima,  the  Yuma,  the  Gila,  and  the  Somerton,  improved  long 
staple  varieties,  originated  as  mutations,  according  to  Kearney  (29,  30,  31),  their 
originator,  and  are  amongst  the  most  important  commercially  in  the  United  States. 

In  tobacco,  the  writer  (47)  in  1904  in  the  Connecticut  Valley  originated  the 
Hazlewood  variety  as  a  mutation  of  the  Cuban  variety.  This  variety  has  fur- 
nished the  foundation  for  one  of  the  important  agricultural  industries  in  America. 
In  1903  and  1904  the  writer  secured  through  the  selection  of  mutations  the  Uncle 
Sam  Sumatra,  which  is  grown  commercially  in  Florida,  Georgia,  and  Alabama ; 
the  Halladay,  which  is  extensively  grown  in  the  Connecticut  \'alley.  and  other 
commercial  tobacco  varieties. 

In  the  cacti,  Griffiths  (27)  records  the  origin  of  several  spineless  varieties 
as  bud  variations  of  spiny  forms. 

In  corn,  Emerson  (21)  records  the  occurrence  of  recurring  somatic  varia- 
tions in  variegated  ears.  De  Vries  (74)  describes  mass  mutations  in  maize 
and  {72))  other  forms  of  mutation,  including  unbranched  varieties,  loss  of  starch 
in  the  grains,  and  dwarf  forms.  East  and  Hayes  (20)  report  various  forms  of 
somatic  mutations  in  corn,  including  dwarf,  bifurcated,  and  branched  ears. 

In  sugar  cane,  Carriere  (8)  mentions  this  plant  as  one  which  shows  a  large 
number  of  distinct  bud  varieties.  Darwin  (15)  states  that  sugar  cane  is  one  of 
several  plants  that  sometimes  produce  new  varieties  from  the  stock  or  root.  He 
quotes  Caldwell  (7)  as  saying  that  the  Ribbon  cane  has  sported  in  Mauritius 
"into  a  perfectly  green  cane  and  a  perfectly  red  cane  from  the  same  head.  I  veri- 
fied this  myself,  and  saw  at  least  200  instances  in  the  same  plantation  and  the 
fact  that  completely  upset  all  our  preconceived  ideas  of  the  differences  of  color 
being  permanent.  The  conversion  of  a  striped  cane  into  a  green  cane  was  not 
uncommon,  but  the  change  into  a  red  cane,  universally  disbelieved,  and  that  both 
events  should  occur  in  the  same  plant,  seemed  incredible.  I  find,  however,  in 
Fleischman's  'Report  on  Sugar  Cultivation  in  Louisiana  for  1848'  by  the  American 
Patent  Office,  the  circumstance  is  mentioned,  but  he  says  he  never  saw  it  him- 
self." 

The  Commissioner  of  Agriculture  for  the  West  Indies  (35)  reported  several 
instances  of  striking  bud  mutations  in  sugar  cane  that  had  recently  come  to  his 
attention,  and  presented  colored  illustrations  of  two  of  them.  (An  abstract  of 
this  article  with  black  and  white  reproductions  of  the  illustrations  has  appeared 
in  the  Journal  of  Heredity  (39).)  These  observations  were  summarized  as 
follows : 


11 

1.  Bud  variations  occur  in  the  sugar  cane. 

2.  Tliey  have  been  recorded  from  widely-separated  countries, — Mauritius, 

Louisiana,   West   Indies,   and   Queensland. 

3.  The  difference  between  sport  and  mother-plant  are  often  as  considerable 

as  those  between  recognized  distinct  varieties  of  the  sugar  cane. 

4.  Bud  variation  may  give  rise  to : — 

(a)  Differently  colored  side  shoots  on  one  cane. 

(b)  Dift'erently  colored  canes  in  one  stool  springing  from  the  same 

mother  plant. 

(c)  A  cane  with  some  joints  striped  and  some  unstriped. 

5.  Plants  grown  from  cuttings  of  the  sports  tend  to  come  true  to  color. 

6.  The  cane  giving  rise  to  sports,  whenever  recorded,  has  been  a  striped  or 

ribbon  cane. 

The  observations  of  other  writers  have  disproven  this  last  conclusion,  as  is 
shown  by  Deerr's  account  of  the  Home  variety  mentioned  below.  Some  bud 
varieties  of  cane  also  show  differences  in  hardiness  and  in  sugar  content. 

Deerr  (  16)  states  that  the  Lahaina  and  Bourbon  varieties  originated  as  bud 
mutations  from  the  Mignonne  variety.  He  records  that  the  yellow-violet 
Cheribon  and  purple-violet  Cheriljun  varieties  orii^inated  as  bud  mutations  of  the 
ribbon  cheribon  variety  and  that  the  white  and  black  cheribon  are  bud  varieties 
of  the  ribbon  cane.  Als(;  that  the  White  Tanna  and  Black  Tanna  varieties  origi- 
nated as  bud  sports  of  the  Striped  Tanna.  The  Rose  Bamboo  and  Purple  Bam- 
boo varieties  arose  from  mutations  of  the  Striped  Bamboo,  and  the  Yellow  Tip 
variety  originated  as  a  bud  mutation  of  the  Striped  Tip.  Deerr  says  that  the 
Home  variety  is  of  particular  interest  because  it  is  one  of  the  earliest,  if  not  the 
earliest,  recorded  instance  of  a  striped  cane  originating  from  a  self-colored  cane 
as  a  bud  mutation.  He  also  cites  the  Green  Rose  Ribbon  variety  originating  as 
a  bud  sport  of  the  Otaheite  variety.  In  the  striped  cane  known  as  the  Tsimbec, 
a  variety  called  the  Iscambine  rouge  arose  from  a  bud  mutation.  He  says  that 
the  Branchu  blanche  is  a  self-colored  sport  from  the  Branchu  rayee.  Further, 
he  records  the  case  of  green  and  yellow  ribbon  cane  springing  from  the  Yellow 
Caledonia. 

In  December,  1890,  Mr.  John  Home  (35),  then  Director  of  Forests  and 
Botanical  Gardens,  Mauritius,  in  a  letter  to  the  Director  of  the  Royal  Gardens, 
Kew.  published  in  the  Kew  Bulletin  for  1891,  wrote:  "Of  new  varieties  orig- 
inating as  bud  sports  we  have  eight  or  nine  in  Mauritius  alone ;  some  of  them 
very  fine  canes  and  they  are  extensively  planted.  Most  of  them  are  hardier  than 
thei,"  ]Darents  and  they  yield  more  sugar.  They  are  mostly  obtained  from  new 
canes  recently  introduced.  The  sudden  change  of  cHmate,  soil  and  other  circum- 
stances cause  them  to  be  thrown  off.  More  of  them  might  be  obtained  if  the 
planters  were  more  observing  than  they  are  and  closely  followed  the  cane  cutters 
throughout  their  fields.  As  things  are,  a  new  variety  is  only  observed  should  it 
chance  to  spring  up  in  an  outside  row." 

The  Hawaiian  Sugar  Planters'  Association  Experiment  Station  has  collected 
a  large  amount  of  information  showing  the  frequent  occurrence  of  bud  mutations 
in  sugar-cane  varieties  grown  in  the  Hawaiian  Islands. 


12 

The  writer  is  of  the  opinion  that  systematic  economic  bud  selection  work 
with  sugar  cane  will  give  particularly  early  and  striking  results  in  the  way  of 
improved  sugar  production  per  acre,  which  will  be  worth  millions  of  dollars 
annually  to  the  industry. 

The  simple  elimination  through  bud  selection  of  some  of  the  undesirable 
strains  arising  from  bud  mutations  in  the  established  varieties  will  in  itself 
achieve  this  result.  This  work  can  be  carried  on  without  any  possibility  of  loss 
to  the  industry  or  the  rearrangement  of  any  of  the  methods  of  culture  other  than 
that  of  securing  seed  cane  for  planting.  The  cost  of  this  work  will  be  very 
small  in  comparison  with  its  value.  The  increased  production  of  sugar  through 
the  culture  of  uniform  and  superior  varieties  will  be  effected  at  no  greater  cost 
than  that  previously  sustained  when  growing  the  more  variable  varieties  with 
their  resulting  lower  yields. 

In  pineapples,  the  writer  observed  in  May,  1920,  amongst  the  plants  in  a 
commercial  field  of  the  Smooth  Cayenne  variety  grown  on  the  Island  of  Oahu, 
T.  H.,  many  apparent  striking  bud  mutations.  The  leaves  of  some  plants  were 
smooth  while  others  were  sharply  serrate.  The  shape  of  some  of  the  fruits  was 
cylindrical,  while  in  other  cases  it  was  pyriform,  ovate,  obovate,  globular,  or 
modifications  of  these  shapes.  About  25  per  cent  of  the  plants  had  no  fruits, 
while  others  were  bearing  fruits  of  dift'erent  stages  of  ripeness.  Some  of  the 
plants  observed  possessed  a  single  crown,  while  others  had  multiple  crowns. 
Frequent  examples  of  plants  having  distinct  strain  characteristics,  apparently 
originating  as  bud  mutations,  were  found,  indicating  that  bud  variation  is  of 
common  occurrence  in  this  variety. 

The  above  list  of  varieties  arising  from  bud  mutations  contains  only  a  few 
of  those  on  record.  Furthermore,  the  recorded  instances  constitute  only  a  small 
part  of  the  total  number  of  such  cases.  This  condition  exists  to  a  large  extent 
because  most  observers  have  not  realized  the  possibility  of  the  occurrence  of  bud 
mutations  and  their  relation  to  the  production  of  new  varieties.  For  this  reason 
it  has  been  quite  generally  believed  that  bud  varieties  are  fixed,  and  any  new 
forms  discovered  in  them  have  usually  been  ascribed  to  seed  origin.  Enough 
instances  have  been  given  to  prove  the  importance  of  bud  mutations  in  plant 
improvement  work,  and  particularly  so  in  the  case  of  those  plants  which  are 
vegetatively  propagated. 

The  Isolation  of  Strains  in  Established  Varieties. 

The  term  strain  as  here  used  designates  a  group  of  individuals  of  an  agri- 
cultural variety  differing  from  all  other  individuals  of  the  variety  in  one  or  more 
constant  and  recognizable  characteristics  and  capable  of  perpetuation.  This  dis- 
cussion will  be  largely  confined  to  vegetatively  propagated  strains  which  in  scien- 
tific literature  are  frequently  referred  to  as  clones,  as  suggested  by  Webber  (76). 

Strains  oftentimes  arise  from  the  unintentional  propagation  of  bud  muta- 
tions. For  example,  the  writer  and  his  associates  have  found  in  their  study  of 
the  Washington  Navel  orange  (64)  that  this  variety  as  grown  under  California 
conditions  has  given  rise  to  fourteen  strains  through  bud  mutation  within  a  few 


13 

bud  generations.  Typical  fruits  of  some  of  these  strains  are  shown  in  Plate  14. 
These  strains  for  the  most  part  have  been  unintentionally  propagated  by  nursery- 
men and  others.  Some  of  them  have  been  found  to  be  very  undesirable  from 
the  economic  standpoint,  while  others  apparently  possess  some  value  for  par- 
ticular conditions  of  culture. 

Varieties  of  economic  value  and  importance  often  degenerate  or  run  out 
through  the  unintentional  or  intentional  propagation  of  undesirable  strains  origi- 
nating as  bud  mutations.  In  the  Washington  Navel  orange  variety  as  grown  in 
California,  the  writer  has  found  that  the  undesirable  Australian  strain,  having 
rank-growing  trees,  an  example  of  which  is  shown  in  Plate  15,  which  character- 
istically bear  small  crops  of  fruit  of  inferior  quality,  as  shown  in  Plate  16,  has  in 
some  instances  been  propagated  to  such  an  extent  as  to  render  the  variety  an 
unprofitable  one.  In  a  few  cases  the  Australian  strain  has  been  intentionally 
propagated  by  nurserymen  because  of  the  vigorous,  hardy  growth  of  the  trees 
and  owing  to  a  lack  of  knowledge  of  their  fruiting  habits.  However,  the  propa- 
gation of  the  Australian  strain  has  usually  been  unintentional.  The  trees  of  this 
strain  produce  unusual  numbers  of  vigorous-growing  branches,  frequently  called 
suckers.  This  growth  was  formerly  highly  prized  and  commonly  used  for  the 
propagation  of  the  Navel  orange  variety  in  California.  Inasmuch  as  the  supply 
of  such  bud-wood  was  much  more  abundant  in  Australian  trees  than  in  the  high- 
yielding  and  desirable  trees,  budders  naturally  secured  more  bud-wood  from  the 
Australian  than  from  the  Washington  or  best  strain  trees  where  it  was  obtained 
without  regard  to   fruit  production. 

The  isolation  of  the  valuable  strains  of  commercial  varieties  through  bud 
selection  is  one  of  the  important  factors  in  plant  improvement  work.  After 
strains  have  been  isolated,  their  value  for  cultivation  determined,  and  their  char- 
acteristics recognized,  they  are  frequently  classed  as  agricultural  varieties. 

In  potatoes,  Myers  (36)  reports  the  results  of  hill  selection  from  high-yield- 
ing and  low-yielding  strains  of  potatoes  in  New  York.  The  Cornell  experiments 
showed  a  five-years'  average  yield  of  three  low-yielding  strains  of  82  bushels  per 
acre  as  compared  with  a  five-years'  average  yield  of  three  high-yielding  strains 
of  208  bushels  per  acre.  The  increase  in  yield  secured  through  bud  selection  in 
these  experiments  amounted  to  an  average  of  126  bushels  per  acre.  Similar  re- 
sults were  obtained  by  Daniel  Dean  (36)  of  Nichols,  N.  Y.,  who  began  hill  selec- 
tion with  his  variety  of  potatoes  in  1904  and  whose  records  show  a  difference  in 
production  in  his  high-yielding  as  compared  with  his  low-yielding  strains  of  280 
bushels  per  acre  in  1912  and  140  bushels  per  acre  in  1913.  The  difference  in  1913 
would  have  been  greater  except  for  an  early  frost.  G.  D.  Brill  in  one  year's  hill 
selection  work  secured  an  increase  of  107  bushels  per  acre  as  shown  by  the  dif- 
ferences in  yields  of  a  high-yielding  as  compared  with  a  low-yielding  strain  of 
the  same  commercial  variety  (36). 

The  comparative  yields  of  high-  and  low-yielding  strains  of  the  Carmen  No.  3 
potato  variety  isolated  through  hill  selection  during  1904,  1905,  and  1906,  are 
reported  by  Waid  (75)  of  the  Ohio  Agricultural  Experiment  Station.  In  these 
experiments   the   high-yielding   strain    produced   a    three-years'   average   of    774 


14 

bushels  per  acre  as  compared  with  an  average  of  492  bushels  per  acre  for  the 
iow-yielding  strain,  and  a  yield  of  607  bushels  per  acre  secured  from  seed  tubers 
selected  without  reference  to  individual  hills.  The  high-yielding  strain  produced 
an  average  of  262  bushels  per  acre,  or  about  35  per  cent  more  than  the  low- 
yielding  strain,  and  167  bushels  per  acre,  or  about  22  per  cent,  more  than  the 
check  as  the  result  of  three  years  of  bud  selection  work.  His  studies  showed 
clearly  that  with  few  exceptions  the  low-yielding  plants  remained  unproductive 
and  that  the  high-yielding  hills  for  the  most  part  remained  productive,  as  was  also 
shown  to  be  the  case  in  the  Cornell  experiments  referred  to  above. 

In  citrus  varieties,  the  writer  and  his  associates  have  recorded  the  behavior 
of  14  strains  of  the  Washington  Navel  orange  (64)  [typical  fruits  of  some  of 
these  strains  are  shown  in  Plates  17,  18,  and  19]  ;  12  strains  of  the  X'alencia 
orange  (65)  ;  7  strains  of  the  Marsh  grapefruit  (66)  [typical  fruits  of  two  of 
these  strains  are  shown  in  Plates  20  and  21]  ;  8  strains  of  the  Eureka  lemon  (67) 
[typical  fruits  of  three  of  the  strains  are  shown  in  Plates  22,  23.  and  24]  ;  and  6 
strains  of  the  Lisbon  lemon  (68)  [typical  fruits  of  several  strains  are  shown  in 
Plates  25  and  26].  These  strains  originating  as  bud  mutations  have,  for  the  most 
part,  been  unintentionally  propagated.  They  have  been  found  to  be  capable  of 
perpetuation  through  bud  propagation.  The  isolation  of  the  valuable  strains  and 
the  elimination  of  the  undesirable  ones  through  systematic  bud  selection  has  been 
demonstrated   to   be  possible   and  commercially   practicable. 

In  timothy,  ^^'ebber  ( 7S' )  found  great  dift'erences  experimentally  and  com- 
mercially in  the  yield  of  high-  and  low-producing  strains  isolated  through  bud 
selection.  Experimentally,  he  shows  that  the  high-yielding  strains  produced 
an  average  of  more  than  six  times  the  yield  of  the  low-yielding  strains. 

In  prunes,  the  writer  has  begun  the  study  of  the  behavior  of  seven  strains 
originating  as  bud  mutations  of  the  French  prune  variety  in  California ;  an 
example  of  one  of  these  mutations  is  shown  in  Plate  9.  The  data  are  incomplete 
as  yet,  but  enough  information  has  been  secured  to  warrant  the  statement  that 
these  strains  are  very  dififerent  in  fruit  and  foliage  characteristics  and  that  these 
differences  are  of  great  con.imercial  importance  to  the  prune  industry. 

In  sugar  cane,  the  writer  and  associates  in  the  Hawaiian  Sugar  Planters' 
Experiment  Station  during  1920  found  in  fields  of  the  H  109,  the  Yellow  Cale- 
donia, and  the  D  1135  varieties  many  plants  resembling  distinct  strains.  Their 
appearance  and  occurrence  indicated  that  they  originated  as  bud  mutations.  The 
plant  differences  found  in  these  strains  included  the  number  of  stalks  of  each 
stool  and  their  habits  of  growth,  weight,  length,  circumference,  shape,  and  color 
of  stalks,  amount  of  juice  in  the  stalks  and  its  sucrose  content,  and  other  impor- 
tant characteristics.  These  data  are  not  complete  as  yet,  nor  available  for  pub- 
lication, but  it  is  likely  that  they  will  be  announced  when  these  investigations 
have  proceeded  far  enough  to  warrant  this  action. 

Most  of  the  work  in  the  isolation  of  strains  has  not  been  reported  because 
such  records  have  usually  been  withheld  until  the  strains  have  been  tested  and 
introduced  as  varieties.     In   strawberries  ( 5,   32),   apples  (41,  42.  43,  44).   and 


15 

other  crops  such  work  has  been  reported  upon,  but  the  writer  feels  that  it  is  not 
necessary  here  to  quote  them  in  order  to  demonstrate  the  importance  of  this 
work.  The  isolation  of  vakuible  commercial  strains  arising  as  bud  mutations  of 
established  varieties  in  vegetatively  pro])agated  i)lants  has  been  found  to  be  prac- 
ticable, and  it  seems  likely  that  the  work  can  be  made  increasingly  useful  when 
once  its  importance  is  more  generally  understood. 

The   ELmiXATioN    of    Undesirable    Strains. 

The  undesirable  strains  in  established  commercial  varieties  arising  from  bud 
mutations  include  those  in  which  the  plants  produce  unsatisfactory  and  unprofit- 
able crops.  For  example,  the  Shade-tree  strain  of  the  Eureka  lemon,  (67)  an 
illustration  of  which  is  shown  in  Plate  27,  which  lias  been  found  by  the  writer 
and  his  associates  to  constitute  more  than  23  per  cent  of  the  population  in  some 
lemon  orchards.  The  trees  of  this  strain  produce  low  yields  of  coarse  thick-rind 
fruits,  lacking  in  juice.  The  culture  of  these  trees  has  been  found  to  be  un- 
profitable wh.cre\'er  investigated  on  account  of  their  poor  production.  A  number 
of  lenion  orchards  have  been  continuously  unj^rofitable  from  this  cause  alone. 
The  elimination  of  the  trees  of  the  Shade-tree  strain  in  estaldished  orchards 
through  top-working  them  with  buds  secured  from  productive  trees  of  the  de- 
sirable Eureka  lemon  strain,  an  illustration  of  which  is  shown  in  Plate  28,  has 
resulted  in  the  development  of  heavy-bearing  trees  and  profitable  orchards. 

In  established  orchards  or  plantations  where  individual  trees  or  plants  of 
undesirable  strains  are  discovered,  such  trees  or  plants  can  be  successfully 
eliminated  by  top-working  with  carefully-selected  buds  or  grafts  secured  from 
desirable  parent  trees,  as  shown  in  Plate  29,  or  by  replanting  with  young  trees  or 
plants  of  a  desirable  strain.  In  the  propagation  of  young  trees  or  plants  the 
elimination  of  the  undesiral)le  strains  can  be  efi:'ected  by  using  as  parent  trees  or 
plants  only  those  individuals  which  are  known  not  to  transmit  the  undesirable 
strain   characteristics. 

Idle  purity  of  commercial  bud  varieties  can  be  maintained  by  eliminating  or 
a\oiding  the  propagation  of  the  undesirable  strains  which  frequently  originate 
as  bud  mutations;  examples  of  such  mutations  are  shown  in  Plates  30,  31,  and  32. 
The  improved  varieties  of  plants  are  the  most  valuable  and  precious  possession 
of  agriculture.  Without  selection  most  varieties  are  known  to  degenerate  and 
run  out,  largely  due  to  the  appearance  of  undesirable  and  unprofitable  strains. 
Therefore,  the  importance  of  purifying  the  proven  and  established  varieties 
through  the  elimination  of  undesirable  strains  must  be  obvious  to  every  thinking 
and  unj)rejudiced  person. 

The  Amelior.vtion  of  Varieties  and  Strains  Through  Bud  Selection. 

The  term  amelioration  of  varieties  and  strains  as  here  used  may  be  defined 
as  the  keeping  up  or  the  bringing  up  of  the  average  performance  of  the  indi- 
viduals to  that  shown  by  the  behavior  of  the  best  individuals  in  the  variety  or 
strain  through  bud  selection.  The  writer  is  of  the  opinion  that  from  a  com- 
mercial standpoint  this  phase  of  plant  improvement  is  the  most  important  one  of 


16 

all.  This  work  can  be  accomplished  (1)  by  means  of  individual  plant  perform- 
ance records  whereby  the  best  individual  parent  plants  for  propagation  can  be 
found,  and  (2)  through  the  propagation  of  the  superior  plants  selected  on  the 
basis  of  performance  records  and  progeny  tests. 

Individual  Plant  Performance  Records. 

Individual  plant  performance  records  for  plant  improvement  work  include 
systematic  records,  for  as  long  a  period  as  is  found  to  be  necessary  in  order  to 
determine  the  inherent  plant  characteristics,  of  the  quantity  and  commercial 
quality  of  the  crop,  the  variability  of  the  product,  the  season  of  production,  the 
habit  of  growth  of  the  plant,  and  any  other  data  likely  to  be  of  value  in  judging 
the  behavior  and  value  of  the  plant.  In  order  to  illustrate  this  work  the  method 
of  securing  individual  citrus  tree  performance  records  as  carried  on  by  the 
writer  and  his  associates  in  southern  California  for  the  past  eleven  years  will  be 
briefly  described  (48,  49,  51,  64).  There  have  been  two  phases  in  the  evolution 
of  this  work— first,  the  investigational,  and,  second,  the  commercial.  In  the  in- 
vestigational work  carefully-selected  plats  of  about  one  hundred  full-bearing  trees 
each  were  located  in  several  of  the  best  commercial  orchards  of  the  Washington 
Navel  orange,  the  Valencia  orange,  the  Marsh  grapefruit,  the  Eureka  and  Lisbon 
lemon  varieties.  These  locations  were  decided  upon  with  particular  regard  to 
environmental  influences  and  cultural  conditions,  so  that  reliable  data  of  inherent 
tree  characteristics  could  be  secured.  The  location  of  two  orchards  in  which  the 
investigational  tree  performance  records  were  secured  is  shown  in  Plate  33. 

Each  individual  tree  in  these  plats  was  given  a  number  so  arranged  as  to 
both  identify  and  locate  it.  This  number  was  painted  on  the  tree  trunks  with 
pure  white  lead  paint,  always  in  the  same  relative  position  and  so  as  to  be  easily 
legible  and  conveniently  found  when  desired. 

The  fruits  from  each  tree  were  picked  by  or  under  the  immediate  supervision 
of  the  writer  or  his  associates  by  expert  pickers  for  the  entire  period  of  the 
investigation.  The  fruits  from  each  tree  were  studied  immediately  after  picking, 
as  shown  in  Plate  34.  They  were  assorted  into  the  standard  commercial  grades 
for  the  variety.  The  fruits  of  each  grade  were  then  assorted  into  the  standard 
commercial  sizes  for  the  variety.  The  weight  and  number  of  fruits  of  each  size 
in  each  grade  were  then  carefully  determined  by  the  writer  or  his  associates.  So 
far  as  possible,  the  same  man  conducted  this  work  in  each  plat  every  year  in 
order  to  avoid  differences  due  to  the  personal  equation.  After  weighing  and 
counting  each  lot,  the  fruits  were  examined  for  variations  and  the  number  of 
variable  fruits  of  each  class  was  recorded,  as  shown  in  Tables  1  and  2.  During 
the  course  of  this  performance  record  work  descriptions  of  tree  and  fruit  char- 
acteristics were  recorded.  These  studies  were  conducted  on  a  total  of  858  Wash- 
ington Navel  orange  trees,  179  Valencia  orange  trees,  253  Eureka  lemon  trees, 
128  Lisbon  lemon  trees,  104  Marsh  grapefruit  trees,  and  a  number  of  trees  of  sev- 
eral citrus  varieties  of  minor  commercial  importance.  These  records  covered  periods 
of  4,  6,  and  8  successive  years,  as  the  circumstances  warranted,  in  order  to  carry 
out  the  purposes  of  this  investigation.     The  work  entailed  a  large  amount  of 


TABLE  1.— OEANGE  PERFOEMANCE  RECORD. 

DATE:  Feb.  24,  1914.     STRAIN:  Washington.     LOCATION:  Highgrove,  California. 

GROWER:   National  Orange  Company.     GROVE:   Vivienda. 

VARIETY:   Washington  Navel.     PLOT:   3.     ROW:   14.     NO.  OF  TREE:   27. 


Orchard 

Standard 

Culls 

Total 

Orchard 

Standard 

Culls 

946 

Number 

58 

38 

Grades 

Total 

1,042 

300 

!            288 

8 

19 

59 

133 

277 

238 

167 

33 

11 

1 

6 
3 

7 

16 
9 

8 
2 
0 
0 

14 

250 
216 
200 
176 
150 
126 
112 
96 
80 

22 

66 

140 

293 

Number 

247 

Sizes 

175 

35 

11 

1 

Total 

946 

., 

38 

1,004 

Orchard 

Standard 

Culls 

461-  8 

24-  7 

Weight 

17-  4 

Grades 

Total 

503-  3 

300 
288 
2.50 
216 
200 

150 

126 

112 

96 

80 

1-10 

5-  6 

19-14 

51-15 

126-10 

125-12 

99-  6 

21-14 

8-  4 

0-13 

1-  1 

0-15 
2-10 
2-12 
6-12 

2-11 

6-  5 

22-  8 

54-11 

Weight 
Sizes 

133-  6 

4-  9 

4-  8 
1-  4 
0-  0 
0-  0 

■ 

130-  5 

103-14 

23-  2 

8-  4 

0-13 

Total 

461-  8 

24-  7          i                17-4 

485-15 

Notes: — Fine  quality. 


Australian    1 

Wrinkled    

Flattened    

Corrugated    

Protruding   3 

Yellow   

Ridged  3 

Ribbed    


1114   boxes. 


SPORTS 

Creased    

Very  smooth    

Coarse    

Raised  section  .... 
Sunken  section  .... 
Raised   and   sunken. 

Y^ellow  section   

Golden   nugget    .... 


Abnormal  shape   1 

Split   navel    7 

Split    side    3 

Pear   shape    

Elliptical    

Long 

Striped     

Off   bloom    


18 


TABLE  2— ORANGE  PERFOEMANCE  RECORD. 

DATE:   1910-1915.     STRAIN:   Washington.     LOCATION:   Higligrove,   California. 

GROWER:  National  Orange  Company.     GROVE:   Vivienda. 

VARIETY:   Washington  Navel.     PLOT:   3.     ROW:    14.     NO.  OF  TREE:   27. 


':  Season 

Season 

Season 

Season 

Season 

Season 

Average 

I  1909-10 

1910-11 

1911-12 

1912-13 

1913-14 

1914-15 

Orchard 

738 

385 

581 

310 

946 

661 

604 

Number 
Grades 

Standard 
Culls 

19 
0 

45 
38 

57 
41 

80 
311 

58 
38 

151 
165 

68 
99 

Total 

757 

468 

679 

701 

1,042 

977 

771 

300 

288 

10 

1 

14 

2 

14 

2 

7 

250 

36 

0 

13 

6 

22 

4 

14 

216 

41 

2 

19 

34 

66 

21 

30 

200 

117 

6 

80 

43 

140 

49 

73 

Number 
Sizes 

176 
150 
126 

141 

189 
49 

13 
66 
15 

174 

54 

77 
98 
80 

293 
247 
175 

98 
165 
252 

116 
156 
104 

112 

111 

98 

131 

25 

35 

120 

87 

96 

40 

135 

59 

15 

11 

69 

55 

80 

23 

94 

22 

10 

1 

32 

30 

Total 

757 

430 

638 

390 

1,004 

812 

672 

Orchard 

382-  7 

271-14 

315-  0 

152-14 

461-  8 

352-  2 

322.6 

Weight 
Grades 

Standard 

7-10 

75-15 

23-11 

34-  7 

24-  7 

78-12 

32.8 

Culls 

0-  0 

23-14 

16-  3 

103-12 

17-4 

69-13 

38.5 

Total 

390-  1 

323-11 

354-14 

291-   1 

503-  3 

500-11 

393.9 

300 

Weight 

288 

2-  9 

0-  4 

3-  5 

0-  7 

2-11 

0-  5 

1.6 

Sizes 

250 

11-12 

0-  0 

4-  2 

1-13 

6-  5 

1-  2 

4.2 

216 

15-  8 

0-12 

7-  0 

11-  1 

22-  8 

7-  1 

10.6 

Expressed 
in   poundf 

200 
176 

48-11 
66-10 

2-  8 
6-  1 

32-11 
32-11 

15-10 
32-  6 

54-11 
133-  6 

18-  8 
41-  7 

28.8 
52.1 

and 

150 

98-  0 

35-  7 

90-  1 

47-  6 

130-  5 

79-  5 

80.1 

ounces 

126 

28-14 

8-  7 

30-  2 

45-  1 

103-14 

139-11 

59.3 

112 

70-11 

62-  2 

79-13 

15-13 

23-  2 

73-  3 

54.1 

Averages 

96 

28-  7 

98-12 

41-  0 

10-  0 

8-  4 

46-  3 

38.8 

m 
decimals 

80 
Total 

18-15 

85-  8 

17-14 

7-12 

0-13 

24-  1 

25.8 

of  lbs. 

390-  1 

299-13 

338-11 

187-  5 

485-15 

430-14 

355.4 

11  Vz  boxes 

11  >4  boxes 

Notes: — Abraham  Lincoln  tree.         Fruit  is  fine  colored,  large,   and  smooth. 


19 

systematic  attention  and  required  sustained  effort.  Some  of  these  records  are 
being  continued  in  order  to  secure  further  and  more  complete  information  upon 
certain  phases  of  tree  behavior  and  additional  data  of  some  tree  and  fruit  char- 
acteristics. 

These  investigations  have  revealed  the  occurrence  and  frequency  of  bud 
mutations  in  the  varieties  studied,  an  example  of  which  is  shown  in  Plate  35,  the 
existence  and  extent  of  occurrence  of  the  various  strains  arising  from  bud  muta- 
tions and  their  comparative  commercial  value,  the  tree  and  fruit  characteristics 
of  the  trees  of  these  strains,  and  other  information  of  fundamental  importance 
to  the  citrus  industry.  In  the  course  of  this  work  improved  methods  of  propa- 
gation have  been  discovered  and  developed,  such  as  the  use  of  fruit-bearing  bud- 
wood  for  pro])agation,  an  example  of  which  is  shown  in  Plate  36.  instead  of  the 
sucker  growth  which  was  formerly  used  for  this  purpose.  Illustrations  showing 
the  method  of  using  this  l)ud-wood  in  propagation  are  shown  in  I'lates  37  and  3S. 
Individual  tree  performance  records  of  pruned  and  unpruned  trees  of  each  of 
the  commercially  important  varieties  led  to  the  discovery  of  the  very  injurious 
and  disastrous  eft'ects  of  early  or  severe  pruning  ( 55,  58,  63)  with  healthy, 
normal  citrus  trees.  This  information  has  resulted  in  the  general  abandonment 
of  such  practices  amongst  citrus  growers.  The  individual  tree  records,  showing 
the  behavior  of  trees  grown  under  dift'erent  methods  of  soil  fertilization,  led  to 
the  origination  by  the  writer  of  an  improved  system  of  applying  organic  ferti- 
lizers in  citrus  orchards  called  the  furrow-manure  method  (53,  56,  62),  which 
has  proven  to  be  more  economical  and  efficient  than  any  formerly  used.  A  study 
of  the  behavior  of  the  fruits  from  the  lemon  performance-record  trees  in  curing 
rooms  led  to  the  discovery  of  the  importance  of  a  uniform  condition  of  atmo- 
sphere humidity  in  the  curing  of  lemons  and  other  citrus  fruits  and  to  the  inven- 
tion of  a  humidifier  for  securing  and  maintaining  the  optimum  conditions  (50, 
59 ) .  Other  results  might  be  cited,  but  the  above  are  considered  to  be  sufficient  to 
show  the  importance  of  this  work. 

The  results  of  the  investigational  citrus  tree  performance  record  work  nat- 
urally led  to  the  development  and  use  of  commercial  tree  performance  record 
work  by  citrus  growers  for  the  following  purposes:  (1)  to  locate  drone  trees  of 
undesirable  strains   in  the  established  orchards   for  top-working  or  replanting; 

(2)  to  locate,  if  possible,  su])erior  trees  as  sources  of  Inid-wood  for  propagation; 

(3)  to  determine  the   results  of  cultural  experiments  or   tree  treatments;   and 

(4 )  to  carry  on  intelligent  individual  tree  care  in  the  orchards.  Up  to  the  present 
time,  1921,  commercial  tree  records  have  been  kept  in  more  than  50,000  acres  of 
citrus  orchards  in  California  and  in  considerable  citrus  acreages  in  southern  Ala- 
bama and  in  Florida. 

In  commercial  citrus  tree  records  the  yield  of  the  individual  trees  in  weight 
or  number  of  boxes  of  fruit  are  recorded  by  the  foreman  of  the  picking  crew  or 
some  other  person  at  the  time  of  picking,  as  shown  in  Plate  39.  Notes  are  made 
as  to  the  production  of  any  striking  variations  observed  in  the  fruits  or  the  trees. 
In  the  investigational  record  work  it  was  found  that  there  is  a  definite  correla- 


20 

tion  of  the  amount  of  yield  and  the  commercial  quality  of  the  fruits,  the  highest 
yielding  trees  usually  producing  the  highest  proportion  of  first-grade  fruits  of 
the  most  desirable  commercial  size.  From  the  commercial  records  of  individual 
tree  production  for  a  reasonable  period,  a  classification  of  the  trees  with  regard 
to  their  value  for  cultivation  can  be  made,  the  undesirable  trees  top-worked  or 
replanted,  trees  located  for  individual  care  and  attention  as  needed,  superior 
trees,  if  any  be  found,  located  as  sources  of  bud-wood  for  propagation ;  and  the 
results  of  tree  treatments  definitely  determined. 

The  Commercial  Utilization   of  Individual  Plant  Records. 

The  commercial  plant  records  may  be  utilized  in  the  origination  of  new 
varieties,  the  isolation  of  valuable  strains,  and  in  the  amelioration  of  strains 
and  varieties.  The  manner  in  which  this  utilization  is  effected  in  the  citrus 
industry  in  California  will  be  briefly  described  (60). 

The  California  Fruit  Growers'  Exchange,  a  cooperative  non-profit  organi- 
zation of  more  than  ten  thousand  citrus  growers,  established  in  May,  1917,  a 
bud  department  of  the  Fruit  Growers'  Supply  Company,  which  is  a  subsidiary 
organization  furnishing  materials  and  orchard  supplies  of  all  kinds  to  the  mem- 
bers of  the  Exchange  at  cost.  The  bud  department  was  established  for  the  pur- 
pose of  carrying  out  commercially  the  results  of  the  investigational  individual 
tree  performance  record  work  in  the  citrus  fruits.  In  order  to  make  this  service 
available  to  the  citrus  industry  as  a  whole  it  was  provided  by  the  Exchange  that 
the  bud  department  should  supply  reliable  buds  secured  from  superior  parent 
trees,  selected  on  the  basis  of  their  performance  records,  to  all  persons  desiring 
them,  whether  they  were  members  of  the  Exchange  or  not.  In  this  way  the 
work  of  the  bud  department  is  a  public  service.  Within  three  years  since  the 
founding  of  the  bud  department  it  has  furnished  more  than  a  million  selected 
buds  to  propagators  at  a  cost  of  five  cents  each  to  members  of  the  Exchange, 
and  for  six  cents  each  to  non-members.  The  buds  have  been  chiefly  used  by 
nurserymen  in  the  propagation  of  nursery  trees  and  to  a  less  extent  by  growers 
for  top-working  undesirable  trees  in  established  and  bearing  orchards.  The  buds 
have  been  secured,  for  the  most  part,  from  superior  parent  trees  found  in  the 
best  citrus  orchards  existing  in  California.  The  parent  trees  have  been  selected 
as  sources  of  bud-wood  from  a  study  of  the  commercial  individual  tree  per- 
formance records  in  these  orchards  and  in  some  instances  from  the  best  trees  in 
the  investigational  performance  record  plats  previously  studied  by  the  writer. 
This  bud  department  has  been  a  success  and  self-sustaining  from  its  beginning. 
The  young  trees  in  the  orchards  grown  from  these  buds  and  others  selected  and 
distributed  by  the  writer  during  preceding  years  have  produced  earlier  and  more 
uniformly  good  crops  of  fruit  than  trees  in  comparative  orchards  which  were 
propagated  in  the  ordinary  way.  The  value  of  this  improved  production,  due  to 
bud  selection  at  this  time,  has  been  estimated  by  Mr.  G.  H.  Powell,  general  man- 
ager of  the  California  Fruit  Growers'  Exchange,  to  amount  to  more  than  one 
million  dollars  annually.  In  connection  with  the  work  of  securing  and  dis- 
tributing selected   citrus  buds,  the  bud   department  maintains   an   experimental 


21 

citrus  nursery  for  the  study  of  problems  in  budding,  stocks,  and  other  phases 
of  propagation.  It  also  furnishes  to  growers  reliable  information  as  to  the 
adaptation  of  citrus  varieties  to  local  soil  and  climatic  conditions,  accurate  data 
as  to  the  production  of  the  varieties  and  the  relation  of  this  production  to  market 
conditions,  and  other  information  of  value  to  the  prospective  planter  or  the 
established  grower. 

Potato  growers  in  Maine,  California,  and  in  several  other  States  have  or- 
ganized successful  cooperative  associations  for  the  purpose  of  making  available 
commercially  the  results  of  bud  selection  work  in  potato  varieties. 

Other  associations  of  growers  or  propagators  in  industries  founded  upon 
varieties  of  plants  originated  as  mutations  are  in  operation  at  this  time.  Amongst 
these  may  be  mentioned  the  Arizona-Egyptian  Cotton  Growers'  Association,  the 
New  England  Tobacco  Growers'  Association,  and  the  Nurserymen's  Bud  Selec- 
tion Association  of  California. 

The  Selection  of  Superior  Parent  Plants. 

The  selection  of  superior  parent  plants  for  propagation  can  be  made  on  the 
basis  of  individual  plant  performance  record  data  and  the  intimate  knowledge 
of  plant  characteristics  gained  in  the  course  of  the  plant  performance  record 
work. 

In  the  citrus,  the  selection  of  superior  parent  trees  is  made  after  an  ade- 
quate number  of  performance  records  have  been  secured.  Only  the  high-yielding 
trees  producing  the  best  commercial  fruits  are  considered  as  sources  of  bud-wood. 
If  the  records  or  other  observations  show  the  production  of  any  markedly  off- 
ty})e  fruits  or  striking  variations,  such  trees  are  immediately  discarded  from  fur- 
ther consideration  as  sources  of  bud-wood  for  propogation.  Only  those  high- 
yielding  trees  which  consistently  produce  uniformly  good  fruits  are  selected  as 
parent  trees. 

Progeny  Tests. 

The  bud-wood  from  each  parent  citrus  tree  is  kept  separate.  The  buds  from 
each  parent  tree  are  used  in  separate  blocks  so  identified  in  the  nursery  that 
the  progenies  can  be  traced  back  to  the  individual  parent  trees.  Examples  of 
the  fine  growth  and  early  fruiting  habits  of  such  trees  are  shown  in  Plates  40 
and  41.  When  the  nursery  trees  are  transplanted  each  progeny  is  kept  separate, 
and  wherever  possible  the  trees  of  each  progeny  are  planted  in  the  orchard  so 
that  at  any  time  the  behavior  of  any  progeny  and  its  parent  can  be  studied.  In 
this  manner,  as  well  as  through  additional  experimental  progeny  tests  now  under 
way,  the  transmitting  power  of  the  parent  trees  can  be  determined.  In  the 
California  citrus  industry  the  foundation  has  been  laid  for  the  future  selection 
of  parent  trees  on  the  basis  of  progeny  records.  It  is  probable  that  through  this 
work  the  most  reliable  sources  of  propagating  material  will  be  secured  that  has 
ever  been  attained  in  any  industry  in  the  history  of  agriculture.  In  this  con- 
nection it  may  be  stated  that  in  addition  to  extensive  cooperative  commercial 
progeny  tests  the  writer  and  his  associates  are  keeping  investigational  individual 


22 

tree-performance  progeny  records  with  5,464  lemon  trees,  450  orange  trees,  and 
about  5C0  trees  of  other  citrus  varieties.  As  soon  as  funds  can  be  secured  for 
this  work,  the  number  of  trees  where  investigational  records  are  kept  will  be 
greatly  increased. 

Similar  investigational  and  commercial  progeny  tests  to  those  carried  on  in 
the  citrus  are  also  being  conducted  with  cotton,  tobacco,  corn,  oats,  wheat,  flax, 
timothy,  and  varieties  of  other  agricultural  crops  under  different  auspices  in 
various  agricultural  districts  of  the  United   States. 

The  Hawaiian  Sugar  Planters'  Experiment  Station  in  1920  made  a  begin- 
ning of  progeny  test  work  with  selected  plants  of  the  Yellow  Caledonia,  H  109, 
D  1135,  and  other  sugar  cane  varieties  grown  in  the  Hawaiian  Islands.  The 
purpose  of  this  work  is  to  establish  and  maintain  reliable  sources  of  propagating 
material. 

The  Scientific  Study  of  Bud  Mutations  and  Bud  Selection. 

The  oversiiadowing  interest  amongst  scientists  in  the  study  of  the  phenome- 
non of  sexual  variations  in  plants  and  the  behavior  of  seedlings  grown  from 
these  variations  during  the  past  century,  has  resulted  in  the  partial  neglect  of  the 
equally  interesting  and  important  field  of  the  investigation  of  bud  mutations  and 
the   characteristics   of   plants   originating   from   them. 

As  the  writer  sees  it,  the  scientific  problems  in  this  connection  include  a 
study  of  the  extent  and  frequency  of  bud  mutations  in  all  of  the  agricultural 
varieties,  an  investigation  of  the  fundamental  causes  of  the  phenomenon  of  bud 
mutation,  and  the  development  of  improved  methods  of  propagation.  This  in- 
vestigational w^ork  should  precede  and  lay  the  foundation  for  the  commercial 
work.  While  this  arrangement  may  apparently  delay  the  utilization  of  bud 
selection,  it  may,  as  a  matter  of  fact,  hasten  the  time  when  economic  results  can 
be  obtained.  The  scientific  studies  of  bud  mutations,  their  origin  and  develop- 
ment, will  probably  result  in  the  discovery  of  simplified  methods  of  bud  selection 
and  insure  protection  from  disappointments  due  to  operations  founded  upon 
defective  plans  based  upon  incomplete  knowledge  leading  to  premature  and 
oftentimes  erroneous  conclusions.  In  some  instances  it  may  be  found  to  be 
feasible  to  carry  on  the  investigational  and  the  commercial  work  simultaneously. 
The  writer  believes  that  such  is  the  case  in  the  work  for  the  improvement  of 
sugar  cane  through  bud  selection.  As  the  result  of  an  experience  covering  more 
than  twenty  years  in  both  the  investigational  and  commercial  work  of  plant 
breeding,  the  writer  wishes  to  emphasize  the  necessity  for  scientific  studies  in 
this  connection  in  order  to  discover  the  underlying  principles  of  bud  mutation 
and  bud  selection  as  a  means  for  establishing  this  work  in  every  instance  upon 
a  sound  and  lasting  foundation. 

Pioneers   in    Bud   Mutation   and   Selection    Work. 

It  seems  fitting  in  this  paper  to  refer  to  the  pioneer  students  of  bud  variation 
and  bud  selection.  No  attempt  will  be  made  here  to  mention  all  of  the  men  who 
have  been  concerned   in   this  activity.     These  names   include   Carriere,   Darwin, 


23 

De  Vries,  Cramer,  Babcock,  Bailey,  Castle,  Collins,  Cook,  Dorsey,  Galloway, 
Kearney,  Shull,  Stout,  Swingle,  and  Webber.  Of  the  men  who  have  been  more 
particularly  concerned  in  the  introduction  and  development  of  commercial  bud 
selection  work,  the  following  names  may  be  mentioned :  Powell,  Burbank,  Fraser, 
Chase,  Winberg,  Farmer,  Coates,  and  Milliken.  To  this  list  many  other  names 
of  important  workers  might  be  added,  but  the  writer  considers  that  sufficient 
names  have  been  given  to  indicate  the  type  of  workers  concerned  in  this  work. 

Sl'MMARV. 

The  fundamental  factors  in  the  economic  work  for  the  improvement  of 
plants  through  bud  selection  are  (1)  the  development  of  new  and  important 
varieties  originating  from  bud  mutations;  (2)  the  isolation  of  valuable  strains 
of  established  varieties  originating  as  bud  variations;  and  (3)  the  amelioration 
of  the  cultivated  varieties  and  strains  by  bringing  up  their  average  production  to 
as  nearly  that  of  the  best  individuals  in  them  as  may  prove  to  be  possible  through 
the  systematic  selection  and  propagation  of  superior  parent  plants. 

The  experience  and  achievements  to  date  in  both  the  investigational  and 
commercial  work  for  the  improvement  of  plants  through  bud  selection,  warrant 
the  belief  that  much  greater  progress  along  these  lines  may  be  expected  in  the 
future  than  has  been  accomplished  in  the  past,  when  the  possil)ilities  of  this  work 
become  more  generally  recognized  and  more  fully  understood. 

The  writer  believes  that  in  the  plants  with  which  he  is  familiar,  asexual  and 
sexual  reproduction  are  fundamentally  alike  in  respect  to  the  extent  and  range 
of  variation,  and  that  equally  valuable  results  have  been  achieved  and  may  be 
expected  in  the  way  of  plant  improvement  from  bud  selection  as  has  been  the 
case  with  seed  selection. 


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Known  as  Opuntia.     U.  S.  Dept.  Agr.  Bui.  31,  24  p.,  1  fig.,  8  pi. 
(28)     Hedrick,   U.   p.     1915.     Remarkable   Sports   of   the   Twenty-Ounce   Apple.     The   Rural 

New  Yorker,  v.  74,  no.  4307,  p.  722.     May  22. 


D.  H.  HILL  LIBRARY 


25 

Kearney,  T.  H.     1910.     Breeding  New  Types  of  Egyptian  Cotton.     U.  S.  Dept.  Agr., 

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no.  4,  pp.   287-302,  pi.   17-25.     July   15. 
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no.  3,  pp.  216-223,  2  col.  pi. 
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July  14. 
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Selection.     West.  N.  Y.  Hort.   Soc.   (Rochester). 
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26 

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813,   88   p.,   22  fig.,   7   pi. 
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Somatic  Variations.     Carnegie  Inst.  Wash.  Pub.  218,  80  p.,  4  pi.    (3  col.).     Oct.  7. 
ToTTY,   Charles   H.     1918.     Ophelia  and   Its   Progeny.     In   The   Am.   Rose   Ann.,   pp. 

96-98. 
DE    Vries,    Hugo.     1901-3.     Die    Mutationstheorie,    2    v.,    illus.     Leipzig.      (Eng.    trans. 

1909-1910.     Chicago.) 
DE  Vries,  Hugo.     1905.     Species  and  Varieties;    Their   Origin   by  Mutation.     Chicago. 
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pp.  465-467. 
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Asso.,  V.   3,   pp.   191-198. 
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V.  18,  pp.  501-503. 
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Cornell  Univ.  Agr.  Exp.  Sta.  Bui.  313,  pp.  337-392,  fig.  86-96,  pi.  1-10.     April. 


EXPLANATION  OF  PLATES 


Plate. 

1.  Branches   of   the  variegated    Shrubby    Althea   or   Eose   of   Sharon    (Hibiscus   syriacus) 

showing  solid  green-leaved  branches  arising  as  bud  variations.     Riverside,  Cal. 

2.  Variations  in  a  Dahlia  plant  -which  have  persisted  during  the  five  years  of  the  life  of 

the  plant.  The  normal  color  of  the  flowers  is  deep  velvety  red,  and  the  variations 
are  white  and  pinkish  white.     Riverside.  Cal. 

3.  Dahlia  flower  of  Le  Grande  Manitou  variety  and  a  bud  variation  found  on  a  plant  of 

that   variety.     Riverside,   Cal. 

4.  A  branch  of  Euonymus  japonica  showing  the  bud  origin  of  the  silver-variegated  horti- 

cultural variety  argenteo-variegatus.  Several,  if  not  all,  of  the  other  sub- varieties 
of  this  plant  originated  as  bud  mutations.     Riverside,  Cal. 

5.  Branches  of  Pittosporum  toiira  var.  variegatiim,  showing  green-  and  white-leaved  bud 

variations.     Riverside,  Cal. 
<3.      A  bush   of  Pittosporum    tobira  var.   variegaium,   which   has   several   green-leaved   and 
white-leaved   branch   sports.     Riverside,   Cal. 

7.  Branches     of     the     oleander     (Nerium     oleander)     showing    (right)    the    normal    green 

foliage  and  (left)  a  variegated  form  found  as  a  branch  variation  in  the  same 
bush.     Thermal,   Cal. 

8.  Winter  Banana  apples,  showing  a  red  and  two  large  fruits  occurring  as  limb  variations. 

C.  H.  Whittum,  Eaton  Rapids,  Mich. 

9.  Prunes  from  a  single  tree  of  a  new  bud  strain,  the  Coates  1418.     Upper  right,  typical 

Coates  1418;  lower  right,  typical  ordinary  French  prune;  left,  four  Coates  1418 
and  one   ordinary  French.     Morgan  Hill,   Cal. 

10.  Thompson    Seedless    grapes,    showing    (left)    the    normal    fruit    and    (right)    a    large- 

fruited  form  discovered  as  a  bud  mutation  and  projiagiited  by  its  owner.  Thermal, 
Cal. 

11.  Bartlett  Pears,  showing   (right)   ordinary  strain,    (center)    oblong  strain,   and    (left) 

sunken  section  occurring  as  bud  variations.     Tehachapi,   Cal. 
32.      Leaves  and  flower  buds    (the  edible  portion)    of  two  strains  of  the  common  artichoke 
(Cynara   scolymus)    found    on    neighboring    plants    and    doubtless    resulting    from    a 

bud  variation.     Riverside,  Cal. 
1.3.      A    representative    tree    of    the    Washington    strain    of    the    Washington    Navel    orange, 

bearing  heavy  crops  of  high-grade   fruit.     Highgrove,   Cal. 

14.  Fruits  showing  variations  occurring  on  a  single  tree  of  the  Thomson  strain  Washing- 

ton Navel  orange.  These  variations  have  been  propagated  and  each  of  the  two 
progeny  trees  are  producing  fruit  of  the  same  character  as  their  several  bud 
parents,  showing  these  forms  to  be  true  mutations.     Highgrove,   Cal. 

15.  Characteristic  trees  of  the  Australian    (left)    and   Washington    (right)    strains   of   the 

Washington  Navel  orange.     Highgrove,  Cal. 

16.  A  typical  fruit  of  the  Washington  Navel  orange  variety  and  an  Australian  fruit  found 

as  a  limb  sport  in  the  same  tree.     Highgrove,  Cal. 

17.  A  basket  of  Washington  Navel  oranges  from  a  tree  of  the  Washington  strain.     River- 

side, Cal. 

IS.  Fruits  of  the  Corrugated  strain  of  the  Washington  Navel  orange  occurring  as  a  limb 
mutation  in  a  tree  of  the  standard  strain.     Highgrove,  Cal. 

19.  Fruit  of  the  Dry  strain  of  the  Washington  Navel  orange,  occurring  as  a  branch  muta- 
tion in  a  tree  of  the  standard   strain.     Riverside,  Cal. 

■20.  Typical  fruit  of  the  Marsh  strain  of  the  Marsh  seedless  grapefruit.  Note  the  desirable 
shape,  thin  skin,  fine  texture,  and  seedless  character.     Highgrove,  Cal. 

21.      A  fruit  of  the  Seedy  strain  of  the  Marsh  grapefruit.     Highgrove,  Cal. 


28 

22.  A  few  of  the  Eureka  lemon  tyjies  that  frequently  occur  as  bud  variations  on  a  single 

tree.     Corona,  Cal. 

23.  Branches    of    the    Variegated    Eureka    lemon    showing    the    characteristic    markings    of 

fruits,  leaves,  and  young  twigs.  This  strain  originated  as  a  branch  mutation  and 
has  been  propagated  through  three  bud  generations.     Corona,  Cal. 

24.  A  Navel  lemon  found  as  a  bud  variation  on  a  tree  of  the  Eureka  variety.     Escondido, 

Cal. 

25.  Typical   lemons   of   the   Lisbon   strain,   the   type    of    the   Lisbon   variety.     Five    other 

strains  of  this  variety  have  been  found  as  bud  variations,  recorded  and  propagated 
during  the  bud  selection  work  of  the  U.  S.  Department  of  Agriculture.  Corona, 
Cal. 

26.  Lisbon  lemons  showing  pronounced  variations  occurring  on  a  single  tree  of  an  inferior 

strain.     Corona,  Cal. 

27.  A  typical  tree  of  the  Shade  Tree  strain  of  the  Eureka  lemon.     The  trees  of  this  strain 

are  vigorous  and  rapid  in  growth  but  low  in  production  and  bear  fruits  of  a  low 
grade.     Corona,  Cal. 

28.  A  young  Eureka  lemon  tree  of  the  Eureka  strain.     Note  the  productive  condition  of 

the  tree  and  the  fine  type  of  fruit.     Corona,  Cal. 

29.  Marsh  grapefruit  top-worked  on  an  imdesirable  tree.     Highgrove,  Cal. 

30.  Euby  Blood  oranges  showing  typical  fruit  and  others  from  a  branch  mutation,  showing 

various  stages  of  dryness,  the  most  of  the  fruit  being  entirely  dry.  Nearby  trees 
bore  heavy  crops  which  were  all  of  the  Dry  strain.     Corona,  Cal. 

31.  Branch  from  a  Euby  Blood  orange  tree  showing  the  occurrence  of  a  Navel  fruit  as  a 

bud  variation.  In  this  way  the  Bahian  Navel  orange  is  frequently  found  in 
Brazil  as  bud  mutations  in  trees  of  the  Selecta  variety.     Corona,  Cal. 

32.  Thomson  orange  tree  in  which  the  entire  upper  part  and  right  side  are  barren  every 

season,  the  lower  left  portion  bearing  normally.     Riverside,  Cal. 

33.  Washington  Navel  orange  orchards  along  the  foothills,  showing  two  orchards  in  which 

individual  tree  performance  records  were  secured  in  the  investigational  work  of  the 
LT.  S.  Department  of  Agriculture.     Highgrove,  Cal. 
3-4.      View  in  a  Washington   Navel  orange   orchard  showing  the  method  of  grading,   sizing, 
weighing,  and  recording  the  production  of  individual  trees  in  the  investigation  per- 
formance record  work  of  the  L^.  S.  Department  of  Agriculture.     Highgrove,  Cal. 

35.  Typical   flowers   of   the   Washington   strain   and   the   Seedy   strain   of   the   Washington 

Navel  orange.  Note  the  abundance  of  pollen  produced  by  the  anthers  of  the 
Seedy  strain,  while  the  flowers  of  the  Washington  strain  do  not  produce  pollen. 
Riverside,  Cal. 

36.  View   in   an   Eureka  lemon   tree,   showing   the   type   of   fruit-bearing  bud-wood   advised 

for  use  in  propagating  from  select  parent  trees.  The  leaves  have  been  cut  from 
one  twig  in  order  to  show  its  characteristics  to  better  advantage.     Corona,  Cal. 

37.  Citrus  propagation:    Cutting  a  bud  from  a  typical  bud-stick  of  fruit-bearing  wood  for 

insertion  into  the  seedling  stock. 

38.  Citrus  propagation:    Steps  in  the  budding  of  a  citrus  nursery  tree  (from  left  to  right)  : 

seedling  stock;  inverted  T-shaped  cut  for  bud;  bud  inserted;  inserted  bud  wrapped 
with  waxed   cloth;    budding  knife.     Riverside,    Cal. 

39.  View  in   a  Washington   Navel  orange   orchard,   showing  the   method   of   securing   com- 

mercial individual  tree  performance  records  in  this  1500-acre  planting.  Highgrove, 
Cal. 

40.  Two-year-old  Eureka   lemon  nursery  propagated   from   selected   fruit-bearing  bud-wood. 

showing  the  flne  tree  development  and  the  early  fruiting  tendency.     Redlands,  Cal. 
Eureka  lemon  tree,  2  years  9  months  old,  propagated  from  select  performance  record 
trees.     Note  fruitful  condition  and  fine  character  of  fruit.     Claremont,  Cal. 


41. 


o  5 


Plate  2.  Variations  iu  a  Dahlia  plant  which  have  persisted  during  the  five  years  of  the  life 
of  the  plant.  The  normal  color  of  the  flowers  is  deep  velvety  red  and  the  variations 
are  white  and  pinkish  white.     Riverside,  Calif. 


Plate  4.  A  branch  of  Euoiujmus  japonica,  showing  the  bud  origin  of  tlie  silver-variegated 
horticultural  variety  fnncntco-varicfjatus.  Several,  if  not  all,  of  the  other  sub-varieties 
of  this  jilaut  originated  as  bud  mutations.     Eiverside,  Calif. 


Plate  5. 


Branches  of  Pitto.spornm   iohlra   var.    r(irir;iat niu.  show- 
leaved    buil    variations.     Eiverside,    Calif. 


oroen-  ami  white- 


5h 


o  o 


s^ 


bJD  & 

">  s 
5  c« 


Plate  12.  Leaves  and  flower  buds  (the  edible  portion)  of  two  strains  of  the  common  arti- 
choke {Cynara  scolyinus)  found  on  neighboring  plants  and  doubtless  resulting  from  a 
bud  variation.     Riverside,  Calif. 


^ 

•^IflBM^' 

M 

^^ 

|H|HSHR^S9KS&Hb_%£^             V  w 

"V;]S^|^fi|H 

^m 

^^^^^ 

/,'^^^^^^Q^S 

m 

1^^ 

k    ^r^vjP"! 

^^S 

mtK^^ 

^^ 

Plate  13.     A  ro]iiT-('iit;it  i  \  r  tier  nt   iiir  Wii-liiii-iiiii  strain  of  the  Washington  Navel  orange, 
bearing  heax  y  crops  of  high-grade  fruit.     Highgrovej  Calif. 


5f  z 


:^    cS 


-*^   bjo  a> 


?  =«  s 


Plate  16.  A  typii-al  fruit  of  the  Washington  Navel  orange  variety  and  an 
Australian  fruit  fouml  as  a  limb  sport  in  the  same  tree.  Highgrove, 
Calif. 


5oQ 

5  3 

r^       !-l 
>       > 


SI 


c3   o 


Plate  21.     A  fruit  of  tlie  Seedy  strain  of  tlie   Marsli  grapefruit.     Highgrove,  Calif 


Plate 


A  few  of  the  Eureka  lemon  types  that  frequently  oeeur  as  bud  variations 
single  tree.     Corona,  Calif. 


Phite  23.  Branches  of  the  V;tiieKated  Eureka  lemon,  showing-  the  characteristic  markings 
of  fruits,  leaves,  and  young  twigs.  This  strain  originated  as  a  branch  mutation  and 
has   been  propagated   through   three   bud   generations.      Corona,   Calif. 


«3 


I  en 


Plate  26.     Lisbon  lemons,  showing  pronounced  variations  occurring  on  a  single  tree   of  an 
inferior   strain.     Corona,    Calif. 


Plate  1^7.  A  tvpiral  tree  of  the  .Sli;i.lc'  Tie,'  >tiaiu  of  the  Kiiieka  lonuni.  The  trees  of  this 
strain  are  vigorous  and  rapid  in  growth  but  low  in  produetion,  and  bear  fruits  of  a 
low  grade.     Corona,  Calif. 


Plate   28.     A   young   Eureka    lemon   tree    of    the    Eureka    strain.     Note    the    productive 
condition  of  the  tree  and  the  fine  type  of  fruit.     Corona,  Calif. 


Plate  29.     ]Marsli  grapefruit  top-worked  on  an  undesirable  tree.     Highgrove,  Calif. 


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Plate 


-'.     Thomson  orange  tree  in  which  the  entire  upper  part   and  right  side  are  barren 
every  season,  the  lower   left  portion  bearing  normally.     Eiverside,    Calif. 


Plate  3(3.  View  in  an  Eureka  lemon  tree,  showing  the  type  of  fruit-bearing  bud-wood 
advised  for  use  in  propagating  from  select  parent  trees.  Tlie  leaves  have  been  cut 
from  one  twig  in  order  to  show  its  character  to  better  advantage.     Corona,  Calif. 


I'late   ;!7.     Citrus   propagation:     ("iittiiig  a    bml    from    a    typical   binl-stick 
wood  for  insertion  into  tlie  seedling  stock. 


Plate  38.  Citrus  propagation.  Steps  in  the  budding-  of  a  citrus  nursery  tree  (from  left  to 
right):  seedling  stock,  inverted  T-shaped  cut  for  bud,  bud  inserted,  inserted  bud 
wrapped  witli  waxed  cloth,  budding  knife.     Eiverside,  Calif. 


Plate  40.  Two-year-ohl  Eureka  lemon  nursery  propagated  from  selected  fruit-bearing  bud- 
wood,  showing  the  fine  tree  development  and  the  early  fruiting  tendency.  Eedlands, 
Calif. 


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